PUTREFACTION. 611 



position of the albuminous molecule runs its course in 

 a varying manner, and leads to the production, some- 

 times of these, sometimes of those, products in largest 

 amount. This varying course of putrefactive processes Varying ^ 

 can be in part occasioned by differences in the fermen- putrefactive 6 

 tescible material, in part, also, by differences in the processes. 

 external conditions ; but the cause of the greatest and 

 most important variations is differences in the kinds of 

 bacteria which set up putrefaction. According as one 

 or other species of bacteria, or a varying mixture of 

 them, gain the upper hand in the putrefying mixture 

 we have a qualitative or quantitative difference in the 

 nature of the products. 



Since we have been able to employ the methods of Multiplicity 

 pure cultivation for the organisms which excite putre- agent^of ^ 

 faction, we have good grounds for believing that we shall Putrefaction, 

 be able to obtain definite proof of the fact that various 

 kinds of bacteria are capable of splitting up albumen, 

 and, at the same time, obtain an insight into the mode 

 of action of each of these kinds. Even now we know 

 a large number of species of bacteria which can, in pure 

 cultivation, occasion a rapid decomposition of the albu- 

 minous molecule, with the formation of foul-smelling 

 gases, but the action of these is very various, whether 

 we look at the nature of the products, or at their quantity. 

 In the case of the majority of these products we require 

 a more accurate knowledge of their chemical nature ; in 

 the case of many it is only the development of foul- 

 smelling gases, the chemical composition of which is 

 not more accurately known, which leads us to assume 

 that a putrefactive decomposition of the albuminous 

 molecule has occurred. The following are examples of 

 these kinds of bacteria : 



Species of bacterium. 



Bacillus putrificus coli 



Bacillus saprogenes, I, II, III. [ 



Putrefactive products as yet 

 demonstrated . 



peptone, ammonia, fatty acids, 

 tyrosine, phenol, indol, sca- 

 tol, &c. (see p. 377). 



foul-smelling gases. 



