40 GLYCOGEN 



within the animal body, as a link in the chain of 

 special problems connected with digestion and nutri- 

 tion, its value was very great. Even greater, per- 

 haps, was its effect as a contribution to general 

 views. The view that the animal body, in contrast 

 to the plant, could not construct, could only destroy, 

 was, as we have seen, already being shaken. But 

 evidence, however strong, offered in the form of 

 numerical comparisons between income and output, 

 failed to produce anything like the conviction which 

 was brought home to every one by the demonstra- 

 tion that a substance was actually formed within the 

 animal body, and by the exhibition of the substance 

 so formed. 



"No less revolutionary was the demonstration 

 that the liver had other things to do in the animal 

 economy besides secreting bile. This, at one blow, 

 destroyed the then dominant conception that the 

 animal body was to be regarded as a bundle of 

 organs, each with its appropriate function, a con- 

 ception which did much to narrow inquiry, since 

 when a suitable function had once been assigned to 

 an organ there seemed no need for further investi- 

 gations. . . . 



"No less pregnant of future discoveries was the 

 idea suggested by this newly-found-out action of 

 the hepatic tissue, the idea happily formulated by 

 Bernard as ' internal secretion.' No part of physi- 

 ology is at the present day being more fruitfully 

 studied than that which deals with the changes 

 which the blood undergoes as it sweeps through 

 the several tissues, changes by the careful adapta- 

 tion of which what we call the health of the body 

 is secured, changes the failure or discordance of 

 which entails disease. The study of these internal 

 secretions constitutes a path of inquiry which has 



