NATURAL HISTORY OF CREATION. 137 



tion of infusoria,* the vegetation called mould, and the 

 like. One seems to be of great force : namely, that the 

 animalcules, which are supposed (altogether hypothe- 

 tically) to be produced by ova, are afterwards found in- 

 creasing their numbers, not by that mode at all, but by 

 division of their bodies. If it be the nature of these 

 creatures to propagate in this splitting or fissiparous 

 manner, how could they be communicated to a vegetable 

 infusion X Another fact of very high importance is pre- 

 sented in the following terms : — '' The nature of the 

 animalcule, or vegetable production, bears a constant 

 relation to the state of the infusion, so that, in similar 

 circumstances, the same are always produced without 

 this being influenced by the atmosphere. There seems to 

 be a certain iwogressive advance in the iwoduciive lyoioers 

 of the infusion^ for at the first the animalcules are only of 

 the smaller kinds, or monades, and afterwards they 

 heconie gradually larger and more coiajdicated in their 

 structure ; after a time, the j^roduction ceases, although the 

 materials are by no means exhausted. When the quantity 

 of water is very small, and the organic matter abundant, 

 the production is usually of a vegetable nature : when 

 there is much water, animalcules are more frequently 

 produced." It has been shown by the opponents of this 

 theory, that when a vegetable infusion is debarred from 

 the contact of the atmosphere, by being closely sealed up 

 or covered with a layer of oil, no animalcules are pro- 

 duced ; but it has been said, on the other hand, that the 

 exclusion of the air may prevent some simple condition 

 necessary for the a])original develo])ment of life — and 

 nothing is more likely. Perhaps the prevailing doctrine 



* The term aboriginal is here suggested, as more correct than 

 spontaneous, the one hitherto generally used. 



