458 ON FERMENTATION-PRODUCING INFUSORIA. 
The propagation of these forms may be effected as in the case of 
yeast. They multiply readily if the medium be appropriate to their 
nourishment. It is a remarkable fact, indeed, that they may be pro. 
pagated ina liquid containing merely sugar, ammonia, and phosphates + 
crystallizable and, in a manner, mineral substances. Their reproduc- 
tion goes on with the appearance of butyric fermentation, the presence 
of which is always clearly manifest ; and although the weight of the 
ferment thus produced (as in other ferments) is always small as com- 
pared with the total weight of the butyric acid, it is still sufficiently 
marked. 
The existence of infusoria possessing the character of a ferment is 
a circumstance in itself well worthy of attention ; but in this instance 
it is rendered the more striking by the fact that these infusoria live and 
multiply without requiring the smallest quantity of atmospheric air or 
free oxygen. It would occupy too much space to explain here, the 
means by which I have guarded against the entrance of free oxygen 
into the solutions and vessels in which these creatures swarm and 
multiply by myriads, but the complete exclusion of this element has 
been thoroughly proved. I will merely add in confirmation, that 
before presenting my results to the Académie, I have obtained the 
testimony of several of its members, before whom I have exhibited 
my experiments, as to the correctness of this assertion. 
Not only do these infusoria live without air, but its presence 
actually destroys them. So long as a current of pure carbonic acid is 
transmitted through the liquid in which they live and multiply, their 
development is in no way affected ; but if, under exactly similiar condi- 
tions, the carbonic acid be replaced by a current of atmospheric air 
for the space of two or three hours only, all perish ; and the butyric 
fermentation, connected with their presence, ceases at the same time. 
We arrive therefore at these two conclusions: 
1. The butyric ferment is an infusorial animal. 
2. This infusorial species lives without free oxygen. « 
The present example is, I believe, the first recorded case of an 
animal ferment, and also of an animal capable of existing without the 
presence of oxygen in the free state.—E. J. C. 
