554 1?RAGMENTS OF SCIENCE. 
stroyiug life 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 indissolably 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 bv 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 illustriobis 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 
which 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 th:ft 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 
