382 THE CAUSES OF THE xi 



already knew as living beings and plants, there 

 were an immense number of minute things which 

 could be obtained apparently almost at will from 

 decaying vegetable and animal forms. Thus, if 

 you took some ordinary black pepper or some hay j 

 and steeped it in water, you would find in the course 

 of a few days that the water had become impreg- 

 nated with an immense number of animalcules 

 swimming about in all directions. From facts of 

 this kind naturalists were led to revive the theory 

 of spontaneous generation. They were headed 

 here by an English naturalist, Needham, and 

 afterwards in France by the learned Buffon. They 

 said that these things were absolutely begotten 

 in the water of the decaying substances out of 

 which the infusion was made. It did not matter 

 whether you took animal or vegetable matter, you 

 had only to steep it in water and expose it, and 

 you would soon have plenty of animalcules. They 

 made an hypothesis about this which was a very 

 fair one. They said, this matter of the animal 

 world, or of the higher plants, appears to be dead, 

 but in reality it has a sort of dim life about it, 

 which, if it is placed under fair conditions, will 

 cause it to break up into the forms of these little 

 animalcules, and they will go through their lives 

 in the same way as the animal or plant of which 

 they once formed a part. 



The question now became very hotly debated. 

 Spallanzani, an Italian naturalist, took up opposite 



