INTRODUCTION 



By Professor D. No£l Paton, M,D., LL.D., F.R.S. 



On looking back over a forty years' association with physiology 

 nothing is more striking than tlie influence which the application 

 of physics has exercised upon the progress of the sciences. 



I well remember that, as long ago as 1878, my first teacher 

 began his lectures on the Institutes of Medicine by defining 

 physiology as the application of physics and chemistry to the 

 study of the body in action. 



But at that time the possibility of applying these sciences was 

 limited. In the first place, their development, and especially 

 the development of physics, was not sufficiently advanced. The 

 dissociation of atoms into ions was hardly recognised, the signili- 

 cance of Graham's colloids was not appreciated, and the pheno- 

 mena of surface tension had hardly been applied to molecular 

 physics. In the second place, physiologists were then generally 

 men trained for medicine, whose education in physics and chemistry 

 had been extremely limited. Of course, there were notable 

 exceptions — e.g. Helmholtz and du Bois Reymond. 



These older physiologists had to be content with recording 

 phenomena rather than with explaining them, and they loved to 

 chronicle their observations in high-sounding Greek names. Can 

 one ever forget the sense of profound knowledge which one enjoyed 

 as a junior student in mastering such terms as " delomorphous " 

 and " adelomorphous " as descriptive of the cells of the stomach ? 

 The so-called chemical physiologists were perhaps the worst 

 offenders. For, having isolated, or thought they had isolated, 

 some constituent of the body of quite unknown chemical consti- 

 tution, they promptly gave it a name with no connection with its 

 chemical nature, and these names have generally continued in use, 

 to the confusion of generations of students. In the present age of 

 " hormones " and " vitamines " one wonders how far the tendency 

 has been eradicated. 



It was the " what happens ? " which interested these older 

 Avorkers : " Why it happens ? " was generally beyond them, and 

 vague theories of some peculiar and special vital action took the 

 place of actual demonstration. 



Undoubtedly the association of physiology with the more exact 



ii. xvii b 



