FEEMENTATION. 265 



destroying life indirectly by the generation of poisonous 

 compounds within the body. This conclusion, which 

 comes to us with a presumption almost amounting to 

 demonstration, is clinched by the fact that virulently 

 infective diseases have been discovered with which 

 living organisms are as closely and as indissolubly as- 

 sociated as the growth of Torula is with the fermentation 

 of beer. 



And here, if you will permit me, I would utter a 

 word of warning to well-meaning people. We have now 

 reached a phase of this question when it is of the very 

 last importance that light should once for all be thrown 

 upon the manner in which contagious and infectious 

 diseases take root and spread. To this end the action 

 of various ferments upon the organs and tissues of the 

 living body must be studied ; the habitat of each special 

 organism concerned in the production of each specific 

 disease must be determined, and the mode by which its 

 germs are spread abroad as sources of further infection. 

 It is only by such rigidly accurate inquiries that we can 

 obtain final and complete mastery over these destroyers. 

 Hence, while abhorring cruelty of all kinds, while 

 shrinking sympathetically from all animal sufifering — 

 suffering which my own pursuits never call upon me 

 to inflict, — an unbiassed survey of the field of research 

 now opening out before the physiologist causes me to 

 conclude, that no greater calamity could befall the 

 human race than the stoppage of experimental inquiry 

 in this direction. A lady whose philanthropy has 

 rendered her illustrious said to me some time ago, that 

 science was becoming immoral : that the researches of the 

 past, unlike those of the present, were carried on with- 

 out cruelty. I replied to her that the science of Kepler 

 and Newton, to which she referred as moral, dealt with 

 the laws and phenomena of inorganic nature ; but that 



