554 FRAGMENTS OF SCTENCti. 



stroyinglife indirectly by the generation of poisonous com- 

 pounds 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 associated as the growth of 

 Torn la 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 impor- 

 tance 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 fer- 

 ments 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 deter- 

 mined, 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 suffering suffering which my own pursuits never 

 call upon me to inflict an unbiased 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 without cruelty. I 

 replied to her that the science of Kepler and Newton, to 

 'vhich she referred, dealt with the laws and phenomena of 

 inorganic nature; but that one great advance made by 

 modern science was in the direction of biology, or the 

 science of life; and that in this new direction scientific 

 inquiry, though at the outset pursued at the cost of some 

 temporary suffering, would in the end prove a thousand 

 times more beneficent than it had ever hitherto been. I 

 said this because I saw that the very researches which the 

 lady deprecated were leading us to such a knowledge of 

 epidemic diseases as will enable us finally to sweep these 

 scourges of the human race from the face of the earth. 



This is a point of such capital importance that I should 



