y [ PREFACE 



passed into oblivion. It was a time of very 

 little interest in such matters, for many lines 

 of development of natural science during the 

 preceding quarter century had conspired to 

 divert attention to other problems. The im- 

 mediate occasion of my interest was, I well 

 remember, the chance reading of Maly's im- 

 portant but almost forgotten papers upon 

 the diffusion and dialysis of phosphates, re- 

 counting phenomena which, in the light of the 

 modern theory of ionization, appeared simple 

 enough, though to their discoverer they had 

 heel in some respects inexplicable. A series 

 of researches have grown out of this interest, 

 ard since that time, whenever freedom has 

 permitted, I have been occupied with various 

 aspects of the problem of the neutrality or 

 /aint alkalinity of the organism. For it soon 

 appeared that the key to the peculiar condi- 

 tions of equilibrium between acids and bases 

 in blood and protoplasm is to be found in such 

 characteristics of phosphate solutions as Maly 

 had observed, and in like behavior of similar 

 solutions containing carbonic acid. When at 

 length it became possible quantitatively to 

 describe the chemical equilibra in such sys- 

 tems, it was at once clear that, of all known 

 substances, phosphoric acid and carbonic acid 

 possess the greatest power of automatic regu- 



