| 单词 | homology |
| 例句 | In addition to their morphological similarity, molecular analyses have revealed similar sequence homologies in their DNA. Fundamentals of Biology 2015-01-01T00:00:00Z To find these implicit pictures, mathematicians use a technique known as persistent homology. How Squishy Math Is Revealing Doughnuts in the Brain 2022-09-26T04:00:00Z Trying to decipher the proper connections, especially given the presence of homologies and analogies, makes the task of building an accurate tree of life extraordinarily difficult. Biology for AP Courses 2022-06-09T00:00:00Z The key to identifying homology is common structure and origin during development, not function. Miller & Levine Biology 2018-01-01T00:00:00Z Serpell and other scientists tend to characterize this position as an overcorrection, but those who espouse it often begin by questioning the homology between dogs and wolves. Dogs live in a human-dominated world. And that’s just fine with them. 2021-08-10T04:00:00Z Sophisticated computer analysis programs determine the percentage of sequence identity or homology. Fundamentals of Biology 2015-01-01T00:00:00Z Mathematician Jose Perea of Northeastern University and a team of computational biologists used persistent homology to find periodic biological processes—those that repeat at regular intervals. How Squishy Math Is Revealing Doughnuts in the Brain 2022-09-26T04:00:00Z Newer technologies can be used to help distinguish homologies from analogies. Biology for AP Courses 2022-06-09T00:00:00Z “Comparing to both of them and showing strong homology to both of them, we’ve kind of covered the range of what one would see in the mouse cortex,” Lein says. Scientists Start Building a Parts List for the Brain 2019-08-21T04:00:00Z The paired pictures share subtleties of form: homologies. Dana Schutz’s Paintings Wring Beauty from Worldwide Calamity 2019-01-21T05:00:00Z Sequence homology can be used to estimate the evolutionary distance between two DNA sequences and reflect the time elapsed since the genes separated from a common ancestor. Fundamentals of Biology 2015-01-01T00:00:00Z This is the description of the chemical based on its topological characteristics—essentially the collection of information gained through persistent homology, such as the number of stubborn holes in each dimension. How Squishy Math Is Revealing Doughnuts in the Brain 2022-09-26T04:00:00Z DNA analysis shows that emus and ostriches share more genetic homology with flying birds which live in the same region than with each other. Biology for AP Courses 2022-06-09T00:00:00Z Eddy, S. R. A new generation of homology search tools based on probabilistic inference. A communal catalogue reveals Earth’s multiscale microbial diversity 2017-10-31T04:00:00Z Bruchpilot, a protein with homology to ELKS/CAST, is required for structural integrity and function of synaptic active zones in Drosophila. Ultra-selective looming detection from radial motion opponency 2017-11-07T05:00:00Z As usual, we’re left with numerous questions about this structure, its homology, origins, its relations to other details of skull anatomy, and its function. The Supracranial Sinus of the Horned Dinosaur Skull 2017-07-22T04:00:00Z After using some standard techniques to simplify the data, the team computed the persistent homology of the system by connecting the data points at different scales and examining the resulting simplicial complexes. How Squishy Math Is Revealing Doughnuts in the Brain 2022-09-26T04:00:00Z This is an example of random DNA homology. Biology for AP Courses 2022-06-09T00:00:00Z I don’t want to put off the Poincaré homology sphere forever, so I’m going to jump in. A Few of My Favorite Spaces: The Poincaré Homology Sphere 2017-06-04T04:00:00Z This is known as the species barrier or the transmission barrier and was initially thought to come from the degree of amino-acid sequence homology between the PrPs of the two species involved26. Mammalian prions and their wider relevance in neurodegenerative diseases : Nature : Nature Research 2016-11-08T05:00:00Z Evolution, homology, and function of the supracranial sinuses in ceratopsian dinosaurs. The Supracranial Sinus of the Horned Dinosaur Skull 2017-07-22T04:00:00Z Since then, Sander and Marks have shown that they can decipher the structure of a wide variety of proteins for which there are no homology templates. This protein designer aims to revolutionize medicines and materials 2016-07-21T04:00:00Z The various metabolic processes and core functions in E. coli share homology with higher organisms. Biology for AP Courses 2022-06-09T00:00:00Z He came up with the first of what are called homology spheres: spaces that have the same homology as spheres but are not topologically equivalent to spheres. A Few of My Favorite Spaces: The Poincaré Homology Sphere 2017-06-04T04:00:00Z The 215 models were then used as a training set for EuGene in order to optimize the different splice site and coding-potential models, as well as the weights for the extrinsic EST and homology evidence. The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea : Nature : Nature Publishing Group 2016-01-26T05:00:00Z Finally, identified LTRs were classified as Gypsy if homology or motif evidence existed for Gypsy and not for Copia, classified as Copia if the opposite were true, and otherwise classified as unknown. Single-molecule sequencing of the desiccation-tolerant grass Oropetium thomaeum : Nature : Nature Publishing Group 2015-11-10T05:00:00Z So-called homology models compare the amino acid sequence of a target protein with that of a template—a protein with a similar sequence and a known 3D structure. This protein designer aims to revolutionize medicines and materials 2016-07-21T04:00:00Z To achieve this, artificial nucleases and an exogenous DNA template bearing homology to the target site and comprising the new sequence76 must be delivered to the cell. Gene therapy returns to centre stage : Nature : Nature Publishing Group 2015-10-13T04:00:00Z Poincaré’s discovery of a homology sphere led him to refine his conjecture to what is now known as the Poincaré conjecture. A Few of My Favorite Spaces: The Poincaré Homology Sphere 2017-06-04T04:00:00Z More specifically, gene functional descriptions were added either manually by consortium expert scientists or automatically through sequence homology searches. The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea : Nature : Nature Publishing Group 2016-01-26T05:00:00Z We first determined sequence homology of the predicted cis-elements in the mouse and human genomes. A comparative encyclopedia of DNA elements in the mouse genome : Nature : Nature Publishing Group 2014-11-18T05:00:00Z The patterns of homology across species and clades were computed. The genome of the recently domesticated crop plant sugar beet (Beta vulgaris) 2014-01-22T18:21:48.441Z Transcripts with homology starting at position one of the Magnoliophyta targets were selected for further analysis. Oil palm genome sequence reveals divergence of interfertile species in Old and New worlds 2013-08-14T18:20:59.500Z Poincaré used the fundamental group of the homology sphere to show that it was topologically different from a sphere. A Few of My Favorite Spaces: The Poincaré Homology Sphere 2017-06-04T04:00:00Z This conclusion relies on phylogenetic analyses that fail to discriminate between homology and homoplasy and further implies virus-like rates of nucleotide substitution in early Paleocene placentals. [Technical Comment] Technical Comment on “The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals” 2013-08-08T17:55:19.813Z When 16 RNAs from different organisms include the same six-letter sequence, it almost always reflects a true homology. Archaebacteria: The Third Domain of Life Missed by Biologists for Decades 2013-01-01T00:45:00.170Z We investigated their potential significance by comparing the homology of barley novel transcriptionally active regions with the rice and Brachypodium genomes that respectively represent 50 and 30 million years of evolutionary divergence. A physical, genetic and functional sequence assembly of the barley genome 2012-12-05T15:22:37.090Z As a secondary analysis, the researchers also looked at bacterial populations in very specific areas of the lung, and found that there was no homology of bacterial species throughout the whole lung. The changing microflora of bacteria in the lungs 2012-10-28T22:45:00.530Z So the Poincaré homology sphere was an important figure in the story of one of the most fascinating areas of mathematical research in the last 100 years. A Few of My Favorite Spaces: The Poincaré Homology Sphere 2017-06-04T04:00:00Z Gene models were obtained by integrating results of de novo gene prediction and alignment-based methods based on homology and transcriptomic evidence. The oyster genome reveals stress adaptation and complexity of shell formation 2012-10-03T18:22:26.103Z One of these relations is called analogy and the other homology, and it is very desirable to bear clearly in mind the distinction which exists between these two relations. The Contemporary Review, Volume 36, October 1879 2012-04-18T02:00:17.060Z Genetic markers and barley gene sequences were positioned to this reference by strict sequence homology association. A physical, genetic and functional sequence assembly of the barley genome 2012-12-05T15:22:37.090Z Improvements in long-range structure were then guided by human homology, placing contigs into scaffolds wherever read pairs confirmed collinearity between gorilla and human. Insights into hominid evolution from the gorilla genome sequence 2012-03-07T18:21:00.777Z In addition to these, there are a number of other cartilaginous pieces present in the head region, the homologies of which are doubtful. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z Whether or not these sorts of limb preferences evolved before the marsupial-placental split, and thus indicate homology, or after, and thus indicate convergence, is not known. Are Wallabies Left or Right Handed? Both! (Sometimes) 2012-01-27T19:15:00.350Z It is open to question, however, how far the evidence from such “heteromorphic regeneration” can be regarded as conclusive on the points of homology. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z We do not here seek for similarity of form, but homology of regions; and it is only by using the same names to denote the same things that we can succeed in determining such homology. Artistic Anatomy of Animals 2011-12-17T03:00:16.893Z Figure 1: Venn diagram summarizing the overlapping homology between the Ascaris suum gene set and those of other nematodes. Ascaris suum draft genome 2011-11-23T18:21:44.707Z They are, however, more superficial in position, and this has led many to doubt their actual homology with the cartilaginous visceral arches. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z The resemblances may be due to the same causes, concerning which future observers may possibly enlighten us, but at present we must regard them as analogies, not homologies. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 2 "Gloss" to "Gordon, Charles George" 2011-10-31T02:00:28.703Z We also expanded both known and novel families by including additional members detected by homology to existing members. A high-resolution map of human evolutionary constraint using 29 mammals 2011-10-26T17:21:43.610Z Homology of names should, in our opinion, always accompany homology of regions. Artistic Anatomy of Animals 2011-12-17T03:00:16.893Z Figure 1: Venn diagram summarizing the overlapping homology between the Ascaris suum gene set and those of other nematodes. Ascaris suum draft genome 2011-11-23T18:21:44.707Z Next came the acknowledgment that even with all the analogies and homologies of structure, seen and unseen, there was a vast chasm between the ape and man. The Relations of Science and Religion The Morse Lecture, 1880 2011-09-11T02:00:11.613Z On the attachments of the Urodele rib to the vertebra and their homologies with the capitulum and tuberculum of the Amniote rib. The Ancestry of Modern Amphibia: A Review of the Evidence 2011-09-10T02:00:27.077Z This mode of spore-formation is totally different from that in the ascus; hence one of the difficulties of the acceptance of Brefeld’s view of the homology of ascus and sporangium. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z The action of the anterior part being clearly comparable to the human great gluteal, there can be no doubt as regards the homology of this portion, so we will not insist on it further. Artistic Anatomy of Animals 2011-12-17T03:00:16.893Z He will be known to many readers as the originator of that theory of cranial homologies which has effected so great a revolution in anatomical science. The International Monthly, Volume 4, No. 3, October, 1851 2011-07-02T02:00:11.323Z In accordance with this, we find in different orders of animal life not merely analogies or resemblances in structure, but homologies or examples of complete identity of structure and function. The Relations of Science and Religion The Morse Lecture, 1880 2011-09-11T02:00:11.613Z There is no published functional annotation of , and its sequence lacks obvious homology to known proteins. Initial genome sequencing and analysis of multiple myeloma 2011-03-23T18:52:33.100Z These facts are important to remember, since we shall presently perceive, upon analyzing their parts, that these Hydræ have a close homology to the Hybocodon. Seaside Studies in Natural History Marine Animals of Massachusetts Bay. Radiates. 2011-03-07T03:00:13.343Z Yet Oken is an eminent physiologist, and has made, it is said, important discoveries in respect to the cranial homologies, which have been developed in Professor Owen’s work on the Homologies of the Vertebrate Skeleton. The Religion of Geology and Its Connected Sciences 2011-02-28T03:00:28.890Z Arguments as to homology, based on derivation or non-derivation from the same embryonic layer, have therefore in themselves but little value. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z These results testify how closely the human organism stands allied to lower orders of organism around; how many homologies of structure there are, and how many analogies in experience. The Relations of Science and Religion The Morse Lecture, 1880 2011-09-11T02:00:11.613Z We find in distinct languages striking homologies due to community of descent, and analogies due to a similar process of 60formation. The Descent of Man and Selection in Relation to Sex, Vol. I 2011-01-17T03:00:49.523Z Although there is the closest homology of parts between the Star-fish and the Sea-urchin, the arrangement of these parts, and the external appearance of the animals, as a whole, are entirely different. Seaside Studies in Natural History Marine Animals of Massachusetts Bay. Radiates. 2011-03-07T03:00:13.343Z Darwin argued that this kind of similarity — known as homology — was just a matter of genealogy. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z The structure of the zooid of Heliopora, however, is that of a typical Alcyonarian, and the septa have only a resemblance to, but no real homology with, the similarly named structures in madreporarian corals. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" If it is a factor, our explanation of the meaning and nature of homology must be fundamentally changed. The Arena Volume 18, No. 93, August, 1897 The structure of the gonopods is unknown, and the homology between the two valves and the skeletal elements of the somites in question not clearly understood. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" In the account of the Nanomia, the homology between its scale, or abortive Medusa, and the Hybocodon, is traced in detail, and I need only allude to it here. Seaside Studies in Natural History Marine Animals of Massachusetts Bay. Radiates. 2011-03-07T03:00:13.343Z Paleontologists, for example, have brought ambiguous homologies into sharp focus with the discovery of transitional fossils. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z The homology existing among the hydrocarbons extends to all their derivatives. Coal and What We Get from It And as similar homologies connect man with all members of the group of mammals, similar blood-relationship must exist. The Arena Volume 18, No. 93, August, 1897 If, assuming descent, this homology were disturbed, and the systematic relationship done away with, for instance through saltatory evolution, the mere fact of descent would not bring the two species any nearer one another. Naturalism And Religion The homologies of the Siphonophoræ or floating Hydroids, with many of the fixed Hydroids, is perhaps more striking when we compare the earlier stages of their growth. Seaside Studies in Natural History Marine Animals of Massachusetts Bay. Radiates. 2011-03-07T03:00:13.343Z In the 1950s, the study of homology entered a new phase. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z I feel much confidence, that the homologies here given are correct. A Monograph on the Sub-class Cirripedia With Figures of all the Species. Similarity in essential structure is known as homology. The Arena Volume 18, No. 93, August, 1897 Kerner disposes of the chief argument in favour of the theory of descent, the homology of individual organs, by explaining that the homology is due to the similarity of function in the different organisms. Naturalism And Religion His comparison of languages may be compared to the earlier labors of students in comparative anatomy who mistook merely external resemblances for structural homology. Noah Webster American Men of Letters Since then, scientists have gotten a far more detailed look at many examples of deep homology. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z I enter on the subject of the metamorphoses the more readily, as by this means alone can the homologies of the different parts be clearly understood. A Monograph on the Sub-class Cirripedia With Figures of all the Species. By the theory of evolution homology, wherever it is found, is proof of blood-relationship. The Arena Volume 18, No. 93, August, 1897 What are the homologies of this form and that? A History of Science, Volume 5(of 5) Aspects Of Recent Science We employ here the terms resemblance, homology and difference in their profound and general sense. The Sexual Question A Scientific, psychological, hygienic and sociological study Our own eyes are also the product of deep homology. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z These productions, so different in their origin, can only be compared from the point of view of the part they play; there are analogies between them but not the least homology. The Industries of Animals With these they should show no homology, as they could have no inheritance in common. The Arena Volume 18, No. 93, August, 1897 In other words, there is homology of structure and analogy of function, conformity to archetypal forms and Teleology of organs, in wonderful combination. Christianity and Greek Philosophy or, the relation between spontaneous and reflective thought in Greece and the positive teaching of Christ and His Apostles Certain purely external resemblances, due to phenomena of convergence, must not be considered as homologies in the sense of hereditary relationship. The Sexual Question A Scientific, psychological, hygienic and sociological study Scientists are also discovering that our nervous system shares an even deeper homology with single-celled organisms. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z If her instincts had centred on him there must be some deeper meaning than passion or even intellectual homology. Black Oxen The homologies among animals are the result of common descent. The Arena Volume 18, No. 93, August, 1897 It is only as "an order of Divine thought" that the doctrine of animal homologies is at all intelligible; and Homology is, therefore, the science which traces the outward embodiment of a Divine Idea. Christianity and Greek Philosophy or, the relation between spontaneous and reflective thought in Greece and the positive teaching of Christ and His Apostles Everywhere we find the distinction between homology and analogy which was explained in the last chapter—the distinction, that is, between correspondence of structure and correspondence of function. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions Until now, scientists have simply stumbled across examples of deep homology. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z In serial homology with the thigh and leg are the bones of the arm and we find that these are undergoing an increase in length commensurate with the increase of the legs. The Biology, Physiology and Sociology of Reproduction Also Sexual Hygiene with Special Reference to the Male These homologies have never been made before, so far as the writer is aware, but they seem natural, and suggested by a careful examination and comparison with the above-mentioned mandibulate insects. Our Common Insects A Popular Account of the Insects of Our Fields, Forests, Gardens and Houses Homonymous: pertaining to homology of parts arranged on a transverse axis similarly developed and of equal function. Explanation of Terms Used in Entomology But Theophrastus shows by many examples that he is capable of following out morphological homologies. The Legacy of Greece Essays By: Gilbert Murray, W. R. Inge, J. Burnet, Sir T. L. Heath, D'arcy W. Thompson, Charles Singer, R. W. Livingston, A. Toynbee, A. E. Zimmern, Percy Gardner, Sir Reginald Blomfield When scientists started sequencing DNA, they were able to find homologies between genes as well. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z They are the homology of the organs, and to a certain degree also the so-called rudimentary organs. The Theories of Darwin and Their Relation to Philosophy, Religion, and Morality Further study, however, of the homologies of these peculiar appendages, and especially a knowledge of the embryological development of Lepisma and Machilis, is needed before this interesting point can be definitely settled. Our Common Insects A Popular Account of the Insects of Our Fields, Forests, Gardens and Houses Hence the homology of the elephant-headed god with the other dragons is further established and shown to be genetically related to the evolution of the protean manifestations of the dragon's form. The Evolution of the Dragon Short ribs occur in the dog-fish, but their homology with those of the rabbit is doubtful. Text Book of Biology, Part 1: Vertebrata “It warms our hearts that deep homology is gaining traction like this,” he said. The Search for Genes Leads to Unexpected Places 2010-04-26T20:22:00Z Thus, then, there is something to be said in opposition to both the aggregational and the mechanical explanations of serial homology. On the Genesis of Species In 1818 he began to discuss philosophical anatomy, the doctrine of homologies; he also studied the embryology of the mammals, and was the founder of teratology. Lamarck, the Founder of Evolution His Life and Work The recognition of the homology of the winged disk with the double axe solves a host of problems which have puzzled classical scholars within recent years. The Evolution of the Dragon D and D' show the fore and hind limbs, to illustrate their homology. Text Book of Biology, Part 1: Vertebrata But we have had to do only with a modification, not with a transformation, of the criterion of homology recognised by the anatomists. Form and Function A Contribution to the History of Animal Morphology The facts of serial homology seem hardly to have excited the amount of interest they certainly merit. On the Genesis of Species But the contest was not so much on the causes of the variation of species as on the doctrine of homologies and the unity of organization in the animal kingdom. Lamarck, the Founder of Evolution His Life and Work I have already suggested the homology between these red berries, the mandrake, and the red ochre of Hathor's elixir. The Evolution of the Dragon Touching the outer sphere, we have Oken's homologies of the cranial vertebra. The Destiny of the Soul A Critical History of the Doctrine of a Future Life Rathke's discoveries relative to the development of the jaws, the hyoid and the operculum, enabled him to make short work of the homologies proposed for them by the transcendentalists. Form and Function A Contribution to the History of Animal Morphology Had they been so, this kind of serial homology might be termed "homogenetic." On the Genesis of Species Analogies and homologies in these phenomena must be accounted for in some other way. On Limitations To The Use Of Some Anthropologic Data The use of this design above the lintel of the gate brings it into homology with the Winged Disk. The Evolution of the Dragon The activities of the group of men that followed Monge were directed toward this end, and we now begin to hear of the great unifying notions of duality, homology, continuity, contingent relations, and the like. An Elementary Course in Synthetic Projective Geometry His brilliant work on the development of the ear-ossicles founded what we may justly call the classical theory of their homologies. Form and Function A Contribution to the History of Animal Morphology The serial homology of the fore and hind limbs is explained by the same writer as the result of a similarity in the influences and conditions to which they are exposed. On the Genesis of Species There are strange analogies; it may be that there are homologies. African and European Addresses Thus we have positive evidence of the homology of the mandrake with red clay or hæmatite. The Evolution of the Dragon He set about studying mineralogy, geology, botany, and was soon observing the homologies of the vertebrate skeleton. The German Classics of the Nineteenth and Twentieth Centuries, Volume 01 Masterpieces of German Literature Translated into English. But some of his homologies showed morphological insight, e.g., his comparison of the "first jaws" of Arachnids to antennæ, because they were placed above the upper lip. Form and Function A Contribution to the History of Animal Morphology The facts to be considered are the phenomena of "homology," and especially of serial, bilateral, and vertical homology. On the Genesis of Species Owen, Agassiz, Carpenter explain the homologies of anatomy and physiology; but a doctrine of the homologies of thought is equally possible, and will sometime be set forth. The Atlantic Monthly, Volume 10, No. 57, July, 1862 But the most definite indication of the mandrake's homology with the pearl is provided by the legend that "it shines by night". The Evolution of the Dragon In one point, however, we must own that he seems slow of apprehension or limited by preconceived opinions,—in his reception of the homologies pointed out by Oken and the Physiophilosophical observers. The Atlantic Monthly, Volume 01, No. 03, January, 1858 "Similarity of development" has become the criterion of homology in the eyes of the embryologist, but "similarity of development" means, not identity of histological differentiation, but similarity of connections throughout the course of development. Form and Function A Contribution to the History of Animal Morphology Very few writers, however, have devoted much time or thought to the question of serial homology in general. On the Genesis of Species A man may live a false life and deceive his most intimate friends in the matter of anatomical analogies or homologies, but he cannot conceal it from the eagle eye of the medical student. Remarks The very essence of such attempts was the institution of a series of homologies and fancied analogies between dissimilar objects. The Evolution of the Dragon Now, the meaning of these anatomical homologies, biologists say, is that these animals are genetically related, that is, they had a common ancestry at some remote period in the past. Sociology and Modern Social Problems Since it is the earliest of these stages that manifest the simplest and most generalised structural relations of the parts, it is in the earlier stages that homologies can be most easily determined. Form and Function A Contribution to the History of Animal Morphology He would explain the serial homologies of such creatures as the lobster and centipede thus: Animals of a very low grade propagate themselves by spontaneous fission. On the Genesis of Species Dear Professor Pelseneer, I am very glad to hear from you that the homology of the cephalopod arms with the gasteropod foot is now generally admitted. Life and Letters of Thomas Henry Huxley — Volume 3 Following up Rathke, he strove to substitute for the then dominant fantastic doctrines of the homologies of the cranial elements advocated by Owen, sounder views based on embryological evidence. Life and Letters of Thomas Henry Huxley — Volume 1 Naturalists differ with respect to the homologies of the digits of birds; but several uphold the view above advanced. The Variation of Animals and Plants under Domestication — Volume 2 But these homologies are still determined solely by the relative positions and connections of the parts, just as homologies are determined in the last of all the stages of development, the adult state. Form and Function A Contribution to the History of Animal Morphology It is much less general and marked than serial, or lateral homology. On the Genesis of Species It is not an important point, but there is to me an irresistible charm in trying to make out homologies. More Letters of Charles Darwin — Volume 2 He had continued the same work by tracing homologies of development in other classes of animals, such as the Cephalous Mollusca, the Articulata, and the Brachiopods. Life and Letters of Thomas Henry Huxley — Volume 1 I rather doubt whether you see how far, as it seems to me, the argument for homology and embryology may be carried. More Letters of Charles Darwin — Volume 1 Coalescence of bones originally separate is one of the most usual events in development, and it is an occurrence which, more than any other, tends to obscure homologies. Form and Function A Contribution to the History of Animal Morphology Secondly, as regards the last-mentioned author's explanation of such serial homology as exists in the centipede and its allies, the very groundwork is open to objection. On the Genesis of Species This may refer to the homologies of the parts. More Letters of Charles Darwin — Volume 2 We find in distinct languages striking homologies due to community of descent, and analogies due to a similar process of formation. The Descent of Man From homologies I should look at it as certain that all mammals had descended from some single progenitor. Life and Letters of Charles Darwin — Volume 2 For Crustacea he established the homologies now accepted, of the mandibles with the mandibles of insects, of the first and second pairs of maxillæ with the parts so named in insects, and so on. Form and Function A Contribution to the History of Animal Morphology Mr. H. Spencer seems to deny serial homology to the mollusca, but it is difficult to see why the shell segments of chiton are not such homologues because the segmentation is superficial. On the Genesis of Species Now is not this structure a good argument that I interpret the homologies of the sides of clinandrum rightly? More Letters of Charles Darwin — Volume 2 How inexplicable are the cases of serial homologies on the ordinary view of creation! The Origin of Species by means of Natural Selection, 6th Edition He thus determined the homologies on the female side. Darwin and Modern Science He did not, however, let this distinction hinder him from asserting the substantial homology of all the gill-arches inter se, the first two included. Form and Function A Contribution to the History of Animal Morphology Thirdly, and lastly, as regards such serial homology as is exemplified by the backbone of man, there are also several objections to Mr. Spencer's mechanical explanation. On the Genesis of Species I must not now indulge myself with looking after vessels and homologies. More Letters of Charles Darwin — Volume 2 The fact that such diverse points of view could direct the observer towards the same result gives, inferentially, a suggestive lesson in what the modern physiologist calls the homologies of parts of the organism. A History of Science — Volume 1 Accordingly, form is one of the least important elements to be considered in determining a homology. Form and Function A Contribution to the History of Animal Morphology But the homologies so drawn repose upon a vague and confused feeling for likenesses; they are not based upon an explicit principle. Form and Function A Contribution to the History of Animal Morphology Similarly the external processes of eolis, doris, &c., are good examples of serial homology, as also are plainly the successive chambers of the orthoceratid�. On the Genesis of Species Further, he does not always remain true to his principles, for he does not establish homologies of parts entirely by their connections but sometimes by their functions as well. Form and Function A Contribution to the History of Animal Morphology The recognition of serial homologies constituted a real advance in morphology; the "philosophical" idea of the repetition of the whole in the parts led to many absurdities. Form and Function A Contribution to the History of Animal Morphology And the surest way to determine the true homologies of parts will be to study their early development. Form and Function A Contribution to the History of Animal Morphology But ordinary methods of comparison fail when the attempt is made to homologise the structure of fishes with that of air-breathing Vertebrates, for the homologies are anything but obvious and no intermediate organs are found. Form and Function A Contribution to the History of Animal Morphology There is no relation of homology between them, because they have no common resemblance as to their relations to surrounding parts, or as to their mode of origin. On the Genesis of Species Parts, therefore, which 127develop from the same "fundamental organ," and in the last resort from the same germ-layer, have a certain kinship, which may even reach the degree of exact homology. Form and Function A Contribution to the History of Animal Morphology Organs can be homologous only within the limits of the big groups; there can be no question of homology between members of different types. Form and Function A Contribution to the History of Animal Morphology The homologies established by this new principle might 166run counter to the homologies indicated by the study of adult structure. Form and Function A Contribution to the History of Animal Morphology In determining homologies Owen remained true to Geoffroy's principle of connections. Form and Function A Contribution to the History of Animal Morphology "Serial homology" is a relation of resemblance existing between two or more parts placed in series one behind the other in the same individual. On the Genesis of Species We may note here that many comparative anatomists of the period were quite ready to decide Huxley's last question in a sense favourable to the older, purely anatomical, view of homology. Form and Function A Contribution to the History of Animal Morphology Owen, for instance, held that difference of development did not disturb homologies established by form and connections. Form and Function A Contribution to the History of Animal Morphology Embryology was of considerable value in helping to determine homologies, but the evidence that it supplied was contributory, not conclusive. Form and Function A Contribution to the History of Animal Morphology As an example of serial homology we might take the centra of the vertebræ—the vomer, the presphenoid, the basisphenoid, the basioccipital and the series of centra in the spinal column. Form and Function A Contribution to the History of Animal Morphology And no investigator of homologies doubts that a considerable number of the bones which form the skull of any osseous fish are distinctly homologous with the cranial bones of man. On the Genesis of Species Thus when the basilar process of the human occipital bone is determined to be the 'centrum' or 'body' of the last cranial vertebra, its general homology is enunciated. Form and Function A Contribution to the History of Animal Morphology We saw that Geoffroy recognised the importance of studying the ossification of the skeleton, and that Cuvier accepted such embryological evidence as an aid in determining homologies. Form and Function A Contribution to the History of Animal Morphology The embryologists were not slow to see that their work threw much light upon questions of homology, and upon the problem of the unity of plan. Form and Function A Contribution to the History of Animal Morphology According to this principle, the homology of a part is determined by its position relative to other parts. Form and Function A Contribution to the History of Animal Morphology The facts of homology, serial, bilateral and vertical, have also been passed in review. On the Genesis of Species In a third paper of about the same time he tried to establish the homologies of the segments throughout the Articulate series—with less success than Savigny. Form and Function A Contribution to the History of Animal Morphology As a true morphologist, however, he held that the principle of adaptation does not suffice to explain the existence of special homologies. Form and Function A Contribution to the History of Animal Morphology He contributed, however, to the common stock a useful analysis of the concept of homology, and established certain classes and degrees of it. Form and Function A Contribution to the History of Animal Morphology They too had recognised homologies of organs; they too had interpreted rudimentary organs as vestiges of an original plan. Form and Function A Contribution to the History of Animal Morphology Animals made-up of parts mutually related in various ways.—What homology is.—Its various kinds.—Serial homology.—Lateral homology.—Vertical homology.—Mr. On the Genesis of Species He distinguished first between general and special homology, in quite a different sense from Owen. Form and Function A Contribution to the History of Animal Morphology This is his definition; but, in practice, Gegenbaur establishes homologies by comparison just as the older anatomists did, and infers common descent from homology, not homology from common descent. Form and Function A Contribution to the History of Animal Morphology He admits that there exists a real homology between, for instance, the notochord of Vertebrates and that of Ascidians. Form and Function A Contribution to the History of Animal Morphology In a series of papers published in 1807, Geoffroy took a further step, and sought to establish homologies which were not obvious—homologies, too, not so much of organs as of parts. Form and Function A Contribution to the History of Animal Morphology This kind of homology is also explained by Mr. Spencer as the result of the similarity of conditions affecting the two parts. On the Genesis of Species But," he adds, "it is too often forgotten 273that homology does not necessarily mean an immediate common origin or close relationship. Form and Function A Contribution to the History of Animal Morphology The germ-layer theory was found inadequate to the new facts, and many reverted to the older criterion of homology based on destiny rather than origin. Form and Function A Contribution to the History of Animal Morphology Coming to morphology proper, Darwin takes up the question of the unity of type, and the homology of parts, for which the unity of type is but a general expression. Form and Function A Contribution to the History of Animal Morphology He admits, however, that Geoffroy has seized upon many hidden homologies, especially by his valuable discovery of the importance of fœtal structure. Form and Function A Contribution to the History of Animal Morphology The word "homology" indicates such a relation between two parts that they may be said in some sense to be "the same," or at least "of similar nature." On the Genesis of Species In the more or the less clear homology, we have the expression of the more or less intimate degree of relationship. Form and Function A Contribution to the History of Animal Morphology Such is, in my opinion, the nature of the homology existing between the tail of the ascidian tadpole and that of Amphioxus or of young amphibians. Form and Function A Contribution to the History of Animal Morphology Much difference of opinion reigned as to the true homologies of the brain and mouth of Annelids and Vertebrates. Form and Function A Contribution to the History of Animal Morphology The first memoir deals with the homologies of the opercular bones. Form and Function A Contribution to the History of Animal Morphology The latter animal is a striking example of serial homology. On the Genesis of Species Special homology, on the other hand, relates to resemblances between organs in different animals. Form and Function A Contribution to the History of Animal Morphology In the former case the homology is said to be "complete," in the latter "incomplete." Form and Function A Contribution to the History of Animal Morphology He proposed, indeed, to do away with the term homology altogether, on the ground that it included many resemblances which were obviously not due to common descent—as, for instance, the resemblance of metameres. Form and Function A Contribution to the History of Animal Morphology True homologies can be established between materials of organisation but not always between organs, which may be composed of different "materials." Form and Function A Contribution to the History of Animal Morphology But there are, it is here contended, abundant reasons for thinking that the predominant agent in the production of the homologies of the limbs is an internal force or tendency. On the Genesis of Species His views were attacked and in some points rectified, but the main homologies he established are even now accepted by many, perhaps the majority of morphologists. Form and Function A Contribution to the History of Animal Morphology The concept of homology has thus a value quite independent of any evolutionary interpretation which may be superadded to it. Form and Function A Contribution to the History of Animal Morphology With the recognition of unity of plan within each group necessarily goes the recognition of what later morphology calls the homology of parts. Form and Function A Contribution to the History of Animal Morphology Almost as a corollary to this comes the further view that form is of little importance in determining homologies. Form and Function A Contribution to the History of Animal Morphology Again, the singular facts of "homology" are capable of a similar explanation. On the Genesis of Species These passages show that Aristotle had some conception of homology as distinct from analogy. Form and Function A Contribution to the History of Animal Morphology What Aristotle sought in the variety of animal structure, and what he found, were not homologies, but rather communities of function, parts with the same attributes. Form and Function A Contribution to the History of Animal Morphology It is important to note this hypothesis of a "metastasis" which Geoffroy makes, for it is the key to the understanding of many of the far-fetched homologies which he tries to establish. Form and Function A Contribution to the History of Animal Morphology Conversely, the same complex of materials, say a fore limb, may take on the most varied shapes according as the function of the organ changes—but homology remains though form changes. Form and Function A Contribution to the History of Animal Morphology Animals made up of parts mutually related in various ways.—What homology is.—Its various kinds.—Serial homology.—Lateral homology.—Vertical homology.—Mr. On the Genesis of Species While Aristotle certainly recognised the existence of homologies, and even had a feeling for them, he did not clearly distinguish homology from analogy. Form and Function A Contribution to the History of Animal Morphology Aristotle took much more interest in analogies, in organs of similar function, than in homologies. Form and Function A Contribution to the History of Animal Morphology |
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