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, 
and steeped it in water, you would find inthe 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 animaleules. 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 
