Fermentation and Kindred Phenomena. 93 



exact information has been obtained of many phenomena which 

 previously were utterly obscure. Some of these phenomena I 

 propose to examine. 



Putrefaction. — This may be considered to be a beautiful 

 device of nature's for disposing of dead organic matter, and for 

 converting it into substances which can again serve for the 

 nourishment of plants and animals. But for it this earth would 

 be a vast charnel-house j we should be surrounded by the em- 

 blems of death, and not only so, but as the supply of substances 

 suitable for the nourishment of plants and animals is limited, 

 each race would gradually diminish the stock, which would 

 eventually become exhausted and the world no longer habitable. 

 As it is, however, no sooner does a plant or animal die or give up 

 its excretions, than the remains are fastened upon by an army 

 of scavengers, who gradually reduce them to simple compounds 

 which are either dissipated in the air, washed away by water, 

 or go to form earth. Every tyro in chemistry knows that every 

 atom of matter is indestructible, " and in its time plays many 

 parts." 



Our army of scavengers are mainly organisms of the kind I 

 have been describing, and although much has been done to- 

 wards their study, much still remains to be done before we shall 

 be able to say definitely what their exact functions are. Thus 

 we do not know at present how many species there may be 

 engaged in the work, nor do we know with any exactness how 

 each species acts. It would appear, however, that putrefaction 

 is by no means a simple process, and that before a complex sub- 

 stance like albumen or white of egg can be resolved into simple 

 bodies like ammonia, water, and carbonic acid it has to be at- 

 tacked by successive gangs of these minute labourers, each gang 

 dying off after completing its share of the work and leaving 

 things in order for the operations of the next. 



If any putrefying substance is examined with the microscope, 

 it is found to be swarming with organisms of nearly all the 

 forms I have described, viz., micrococci, bacteria, bacilli, spir- 

 illa, &c. 



Hauser has devoted much time to the study of putrefactive 



