56 



carbo-hydrates of food, and follow the proteids into the animal 

 stomach where it is the special function of the pepsin contained in the 

 gastric juice to render them soluble. 



A word or two may not be out of place here regarding the digestive 

 ferments. These are all nitrogenous bodies as is also the disatase of 

 malt ; but they are unorganised ferments or enzymes. They are quite 

 different from the organized ferments, the vegetable or animal growths 

 such as Saccharomyces cerevisiw, which are said to provoke the 

 various kinds of fermentations. Perhaps a good way to classify them 

 would be to call the former ferments and the latter "varmints." 



It does not appear that the digestive fluids of the intestinal canal 

 such as the bile and pancreatic juice, are much concerned in acting 

 upon the albuminoids of food or rather the peptones of the chyle. 

 Their functions seem to be rather to convert sugar and fat into 

 a condition for easy absorption. Elaboration follows absorption and 

 ultimately these nutritive materials become part of the blood which 

 conveys them to every part of the body, and affords to every organ and 

 tissue a supply of the substances they stand in need of. Thus the 

 nitrogen we have been following becomes part of the albuminoids of 

 the blood, muscles and nervous system, and to its functions and 

 transformations in connection with these I have now to invite your 

 attention. 



The blood, which constitutes about one twelfth of the weight of 

 the body, and consists of the slightly yellowish colored fluid called the 

 plasma or serum, and the blood corpuscles which swim around in it, is 

 the fluid of life. It not only conducts to the various tissues and organs 

 the substances which are necessary to their sustentation and growth, 

 together with the oxygen required for changing the condition of the 

 waste which they sustain, but it also takes up and removes from them 

 all the substances which have served their purpose and become waste, 

 in order to conduct them to the various organs of removal, the lungs, 

 the "skin and the kidneys, through which they obtain egress from the 

 animal body. Formerly it was supposed that the various combinations 

 and decompositions necessary to those operations took place in the 

 blood itself. This view has, however, long since been recognized as 

 erroneous, for none of the products of such decompositions are ever 



