THE NEW PHYSIOLOGY. 67 



normals we have obtained deeper and deeper insight into 

 the physiology of breathing. We have done this, not 

 by merely seeking for causes in the physical sense, but 

 by seeking for interconnected normals and their organisa- 

 tion with reference to one another and to other organic 

 normals. These normals represent, not structure in the 

 ordinary physical sense, but the active maintenance of 

 composition. We may fitly call this living structure, 

 since so far as we know all living structure is actively 

 maintained composition, the atoms and molecules enter- 

 ing into which are never the same from moment to 

 moment, according to the physical and chemical inter- 

 pretation. Our method has thus been essentially the 

 same as that of the anatomist who seeks for the normal — 

 the type— which runs through and dominates the variety 

 of detail which he meets with, and who reaches more and 

 more fundamental types. 



I wish, now, to point out that the same method has 

 been applied, and is being applied, to other departments 

 of physiology, even though the physiologists applying 

 it may have failed to realise the far-reaching significance 

 of their results. 



I will refer first to the general plrysiology of the blood. 

 The facts that the hydrogen ion concentration and 

 capacity for carrying C0 2 are very accurately regulated 

 in the blood are no isolated facts in physiology, although 

 the accuracy of our physiological means of measurement 

 renders them peculiarly striking. Claude Bernard, in 

 his Leqons sur les phenommes de la vie, was, I think, the 

 first to point out clearly that the composition of the 

 blood, as well as its temperature, is physiologically regu- 

 lated. He was led to this conclusion more particularly 



