4 BUETON EDWARD LIVINGSTON 



now as did the less thoroughly analyzed problem to the writers 

 of a few decades ago. The physiology of the present day has 

 largely to do with the apphcation of physical and chemical 

 principles and methods to the phenomena occurring in organisms, 

 and this application necessitates the analysis of complex processes 

 into their components, as far as this is possible. 



Meanwhile, physical and chemical science have been advancing 

 with rapid strides and have placed a w^iole world of precise 

 quantitative knowledge in the hands of the^physiologist, so that 

 the latter now requires a far better acquaintance with the litera- 

 ture of the physical sciences than with that of plant and animal 

 morphology. Progress has been so rapid and in so many widely 

 different directions that there results, for the present, a sort of 

 confusion, whereby the same phenomenon may be interpreted 

 in widel}^ different terms by different investigators. This state 

 of affairs has led to a much more tentative attitude of mind 

 among natural scientists in general, and especially among 

 physiologists, than formerly prevailed. We have learned to 

 state our conclusions tentatively, and as limited by certain 

 suppositions, and we are not surprised if they require restate- 

 ment within a few years. Nevertheless, we need not be dis- 

 couraged, for progress clearly lies in just this continued rein- 

 terpretation and readjustment of our knowledge. 



The outstanding fact, in this connection, seems to be that 

 physiology deals with greater complexity than does any other 

 natural science — since it has to do wdth the most complex mate- 

 rials and processes so far known to man — and the precise state- 

 ment of physiological relations involves a far larger number of 

 dependent variables, or arguments (in the mathematical sense), 

 than are required in the other sciences. In spite of the great 

 progress already made, we must regard physiology as a very 

 youthful science and we must be content that it blunders and 

 stumbles now and then as it moves forw^ard. 



Complexity of the printed records. One of the greatest changes 

 to which science has been subjected in recent decades hes not 

 so much in the complexity of the things dealt with as in the 

 complexity of our records of scientific knowledge. Of the mak- 



