PROBLEMS OF PHYSIOLOGICAL CHEMISTRY. 153 



from the beaten course, and turning out year after year a definite line 

 of products for the specific purpose in view. Why is it that the 

 epithelial cells of the salivary glands always manufacture mucinogen 

 and ptyalin; the gastric gland cells pepsinogen, renninogen and hydro- 

 chloric acid; the cells of the pancreas trypsinogen and steapsin; the 

 hepatic cells bilirubin, biliverdin and the specific bile acids; the cells 

 of the thyroid iodothyrin, and the cells of the adrenals epinephrin? 

 Essentially the same blood and lymph bathe all these cells with a 

 like nutritive pabulum, and yet each group of cells performs its own 

 line of work, never going astray, in health, and never even temporarily 

 producing a product which rightfully belongs to the other class of 

 cells. Are we to suppose that all these varied products are manufac- 

 tured from the same cell protoplasm, from a common stock, that each 

 one owes its origin to some particular force controlled by extra-cellular 

 influences, each group of cells' being made to manufacture a given 

 product out of the same mother substance ? Or, on the other hand, are 

 we to assume that each group of cells, as it is developed, has as a birth- 

 right the quality of producing from its particular protoplasm a certain 

 line of products, simply because of the peculiar chemical nature or 

 constitution of that protoplasm ? 



In other words, do all the intricacies of cellular activity depend pri- 

 marily upon the character of the anabolic processes by which that 

 protoplasm is built up out of the food materials by which the cells are 

 nourished? It may be just as difficult to explain why and how the 

 cells are able to manufacture a specific protoplasm out of a common 

 pabulum, but the main problem which confronts us is surely capable 

 of being solved. We need to know how far the primary cell constituents 

 of different groups of cells, of the different organs and tissues are 

 similar or unlike each other. If it is shown that the primary cell 

 constituents differ for each glandular organ and tissue, that each group 

 of individualized cells has a protoplasm characterized by some specific 

 feature, then we shall have reason to believe that the anabolic processes 

 are as much, if not more, responsible for individuality of function than 

 the katabolic processes. We may conceive of all protoplasm being built, 

 so to speak, on a certain general plan of structure, but with side chains 

 of varying nature, and that these side chains determine in a measure 

 the character of the katabolic or alteration products that result from 

 the natural activity of the cell protoplasm. In other words, if this con- 

 ception be true, it is the chemical constitution of the cell protoplasm 

 that is primarily responsible for the character of the changes that take 

 place in all active tissues and organs. The extent of oxygenation as 

 influenced by the circulating blood, the direct and indirect influence of 

 various nerve fibers, etc., may all act as modifying agents, but only to 

 the degree of accelerating or inhibiting the rhythmical process which 



VOL. ZXVI. — 11. 



