402 THE AMERICAN NATURALIST [Vol. XLII 



plicable have been clarified. It is futile to deny future 

 rapid progress along the same lines, and the solving of 

 problems that now defy the ingenuity of the experi- 

 menter. We confess our ignorance and our frequent 

 failures, but we believe that we are on the right track. 

 Physics and chemistry are not completed sciences. Their 

 youth indeed is hardly passed. Their greatest achieve- 

 ments are probably yet to come. If what we know of 

 physical mechanism to-day is not sufficient to insure us 

 an understanding of the physiological machine, then let 

 us look to what we shall learn to-morrow. Whatever the 

 ultimate outcome, the solace of the vitalistic conception, 

 it seems to me, should be resisted until we are prepared 

 with full knowledge to maintain the final inefficacy of the 

 physico-chemical mode of interpretation. If such a time 

 ever arrives, it must necessarily be far in the future. 



If the vital process be capable of a physico-chemical 

 interpretation, it is at once understood that the methods 

 of the physiologist must be the methods of physics and 

 chemistry. And this is the case. In the physiological 

 laboratory we employ the same methods that are used 

 in the physical and the chemical laboratories, modified 

 only in so far as is necessary to adapt them to the ma- 

 terial employed for study and the specific problems to 

 be solved. Specific physiological apparatus of precision 

 in great variety has been devised, and specific methods 

 of using it. But the apparatus and methods are physical 

 and chemical in essence. The physiologist's material for 

 study must necessarily be living material, except in so 

 far as it is possible to deduce the vital phenomenon from 

 the phenomena of non-vital substances— a procedure 

 which, though often necessary, as is especially the case 

 in much of the work of the chemical physiologist, is a 

 procedure of limited value. In external and in much of 

 internal physiology the living organism is used intact. 

 With many problems of internal physiology, however, 

 the method of vivisection must be employed— a method, 

 which, notwithstanding the occasional charges of the un- 



