66 INFUSORIA. PART in. 



microscopic fungi are ferments, aiding greatly in the 

 decomposition of organic matter. They however are 

 by no means the only agents in decomposition. The mo- 

 ment life is extinct in an animal or vegetable, Infusoria 

 of the lowest grade seize upon the inanimate sub- 

 stance, speedily release its atoms from their organic 

 bond, and restore them to the inorganic world whence 

 they came. The ferment which transforms lactic acid 

 into butyric acid is a species of vibrio which abounds in 

 "bhe liquid, isolated or united in chains ; they glide, pirou- 

 ette, undulate, and float in all directions, and multiply 

 by spontaneous division. Yibrios possess the unprece- 

 dented property of living and propagating without an 

 atom of free oxygen; they not only live without air, 

 but air kills them. This singular property forms an 

 essential difference between the Vibrios and the Myco- 

 derms : the former cannot live in oxygen ; the latter 

 cannot live without it, and as soon as it is exhausted 

 within the infusion, they go to the surface to borrow it 

 from the atmosphere. 



There are also two groups of Infusoria which possess 

 these opposite characters, one being unable to live in 

 oxygen, while the other cannot live without it ; some- 

 times they even inhabit the same liquid. When the 

 tartrate of lime is put into water along with some 

 ammoniacal and alkaline phosphates, a Monad, the 

 Bacteria terma, and other Infusoria appear after a time. 

 These little animals bud rapidly in an infusion of animal 

 matter, then a slight motion is produced by the ap- 

 pearance of the Monas corpusculum and the Bacterium 

 terma, which glide in wavy lines in all directions in 

 quest of the oxygen dissolved in the liquid, and as soon 

 as it is exhausted they go to the surface in such numbers 

 as to form a pellicle, where by aid of the oxygen they 

 form the simple binary compounds water, ammonia, and 

 carbonic acid. In the meantime the Yibrios, which are 



