January 12, 1917] 



SCIENCE 



29 



method employed at need, and a part of 

 any science that uses them. 



"We have next the use of methods of pre- 

 cision. This may imply the use of a piece 

 of apparatus, or a reaction that has been 

 of service in another science. The use of 

 such a piece of apparatus may suggest 

 itself synonymously with the needs which 

 it was intended to meet. Thus; if in one 

 of our biological products we have reason 

 to wish to measure total nitrogen or amino 

 nitrogen, we should undoubtedly turn to a 

 chemist who would suggest the Kjeldahl 

 or' the Van Slyke methods. The reference 

 suggests at once what I should regard as 

 the best method of reapplying the methods 

 of one science to another science, namely, 

 collaboration, or intimate contact with 

 specialists in various branches. The man 

 who thinks he is trained in one science by 

 having passed through it a few years be- 

 fore, may well fall into the error of using 

 methods he has learned rather than better 

 methods since discovered and currently 

 employed by specialists. A personal ex- 

 ample may illustrate this fact. A few 

 years ago one of my associates and I were 

 working on a problem which finally re- 

 quired a chemical estimation of the amount 

 of glycogen in the liver. This determina- 

 tion necessitates the rapid reduction of 

 glycogen to glucose, followed by its quan- 

 titative estimation from the amount of 

 copper oxide reduced. Fehling's tech- 

 nique had been the classical method fol- 

 lowed in such estimations. Not trusting to 

 our own judgment as to superiority of this 

 method, we consulted a graduate student 

 in the department of biochemistry who 

 was working constantly with glucose de- 

 terminations of this sort, and, following 

 his advice, adopted the modification of 

 Fehling's method which had recently been 

 made by Bertrand. A few months later, 

 on visiting a large eastern hospital where 



determinations of the amount of glucose 

 in the blood were being carried out, I 

 learned that six months' data had just been 

 discarded, owing to the fact that the phy- 

 sician who was conducting the experiments 

 had trusted his rather unusual training in 

 biochemistry and had overlooked Ber- 

 trand 's important modification, which he 

 later adopted and which we employed 

 throughout our study, owing to the fact 

 that we had deferred to the opinion of a 

 specialist. 



It is doubtful if methods of experimen- 

 tation, purely speaking, can be carried 

 over from one science to another. We 

 have stated that the methods of discovery 

 in the broader sense are the same in all 

 sciences, however different the component 

 factors may be. In methods of experimen- 

 tation, however, variation in factors counts. 

 I have constantly been struck with the fact 

 that the chemist experiments in a manner 

 that is essentially different from the one 

 which my work demands. Chemistry is a 

 far more exact science than experimental 

 pathology in the sense that the factors with 

 which chemistry deals are better known. 

 It is interesting to note, however, that a 

 chemist may, and frequently does, accept 

 certain biological evidence as proved which 

 we should reject as inconclusive, owing to 

 the omission of certain controls or cheeks. 

 This difference in viewpoint is dependent 

 on the failure of the chemist to appreciate 

 certain fluctuations in living material which 

 it is impossible now and will perhaps to 

 some extent ever remain impossible to de- 

 termine at a given moment. It does not 

 suffice, moreover, to determine the mean 

 of such a variation in a great number of 

 instances, for the purpose of obviating 

 controls in a given experiment. 



In dealing with the interactions of two 

 substances in chemistry we have to begin 

 with, under the simpler and usual condi- 



