156 SECTIONAL ADDRESSES. 



The bulk of this information has been attained by the deliberate and 

 careful investigation of animals by experimental methods, and as I am 

 going to plead the cause of human physiology may I say at once, lest 

 you should misconceive my purpose, that I do not believe that progress 

 in physiology and in medical science to the lasting benefit of mankind is 

 possible without employing such methods. But, while acknowledging 

 the great debt which we already owe to these investigations, and my firm 

 conviction that their further prosecution will be fully justified in the 

 future, I have to face the question whether the method has not in reality 

 some limitations. 



We are bound, I think, to admit frankly that direct observation bv 

 methods involving operative procedure on the anaesthetized animal cannot 

 by itself give us the full answer that we require. I have defined physiologv 

 as the study of the nature of the phenomena which characterize norma! 

 life, and normal life involves constantly varying activity of all the different 

 organs of the body. Under the influence of an anaesthetic our subject is 

 no longer normal, and we have perforce deliberately to close our eyes to 

 that fundamental aspect of life — ceaselessly varying natural activity. We 

 are forced to adopt methods of investigation which are essentially highly 

 artificial ; the stimuli which we employ are usually coarse, and the changes 

 to which we subject the organs gross, compared with the delicate altera- 

 tions to which these same organs respond in natural life. But even if we 

 admit this, are we to condemn the method ? Certainly not, in my opinion, 

 provided always that we recognize that there is this risk of abnormality 

 and artificiality, and honestly ask ourselves the question — what is the 

 precise significance of our results in relation to normal life ? how far do our 

 observations really help us to understand the phenomena associated with 

 the natural existence of the organism ? We may be accumulating facts ; 

 can we translate them ? 



If we are to understand life we must ultimately adopt methods of 

 investigation which do not interfere with the normality of the organism 

 or its power of self-maintenance ; and clearly, so long as we keep this aim 

 before us, we are perfectly justified in making our observations on any 

 animal the study of which we think will help to solve our problem. The 

 conditions will be satisfied so long as our experimental treatment, whether 

 that involves operative procedure or not, does not materially prejudice 

 the delicate regulation of bodily functions which is so evident in the 

 normal intact animal. Pavlov's classical researches on the secretion of 

 the digestive juices were principally made on dogs which, though previously 

 subjected to operation, were yet capable of exhibiting the normal functions 

 and activities of life, and the requisite conditions were therefore just as 

 effectively fulfilled as in, for example, the fundamental observations made 

 by Rubner on nutrition and energy liberation when absolutely intact 

 animals served as subjects. And yet, in spite of such examples, the point 

 which I want to emphasize is that in the study of normal physiology man 

 is in many instances a far more advantageous subject for investigation 

 than are the lower animals. 



It may be urged that, so far as concerns the natural variations in 

 activity of everyday life, we may study the lower animals just as profitablv 

 as man. But can we guarantee that any animal, even though highlv 



