Antonie van Leeuwenhoek

If we now plainly perceive that the passage of the blood from the arteries into the veins of the tadpole is not performed in any other than those vessels, which are so minute as only to admit the passage of a single globule at a time, we may conclude that the same is performed in like manner in our own bodies and in those of other animals.

In treating of the oak, I have considered that the species of it growing in warm climates is superior to that which is produced in cold countries. But we must not imagine this to be the case with all woods; on the contrary, the fir timber grown in cold countries is superior to that produced in warm ones, where its growth is rapid.