I liken it to getting blood from a stone.

我把它比作从石头中取血。

I liken it to gain blood from a stone.

我把它比作从石头里吸血。

The capacity to get genetic material, that stuff in Madagascar is really hard. I liken it to getting blood from a stone.

在马达加斯加，获得遗传物质的能力是非常困难的。我将其比作从石头里榨血，极其艰难。