PREFATORY NOTE 



THIS book makes no pretensions to be a complete or even a 

 systematic survey of Biophysics. Its object is partly to be 

 explanatory. Current medical publications are full of terms 

 culled from physico-chemical and physical terminology ; the 

 clinician of to-day clothes his ideas in words unknown to his 

 brethren of yesterday ; his phraseology, at least, is physical. 



Apart from and beyond a mere explanation of physico-chemical 

 terms, an attempt has been made in the following pages to present 

 physiological phenomena from a purely physical standpoint. 

 The problems of life, and vertebrate life in particular, have been 

 viewed through a physicist's eyes. This does not necessarily 

 imply that the matter of the book is permeated with mechanistic 

 philosophy. We are all, more or less, amateur philosophers, but 

 we would be poor scientists indeed if our " views " were permitted 

 to colour our facts. Phenomena, as they appear to-day, are set 

 out for the critical examination of the student. " He will have 

 all the facts and circumstances fully mobilised, standing up side 

 by side before him like an awkward squad, and there is nothing 

 more awkward than some facts that have to stand out squarely 

 in the daylight ! And he inquires into their ancestry, makes them 

 hold out their tongues, and pokes them once or twice in the ribs, 

 to make sure that they are lively and robust facts capable of 

 making a good fight for their lives. He never likes to see one 

 thing too large . . . lest he sees something else too small ; but 

 will have everything in true proportion." (David Grayson.) 



It is a great pleasure to me, on reading over the final proofs, 

 to notice how generously my masters and colleagues have come to 

 my aid. Quite apart from the direct help given me by Professors 

 Noel Paton and E. P. Cathcart, who contribute the opening and 

 closing chapters of the theoretical part of the book, I have 

 received daily encouragement from them in my task, for which I 

 express my sincere gratitude. If this effort to make plain the 



