338 PHYSIOLOGICAL CHEMISTRY 



breadth 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, rennino- 

 gen, and hydrochloric 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 w r ith a like nutritive pabulum, and yet each group of cells per- 

 forms 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 manufactured from the same cell protoplasm, from a common 

 stock, that each one owes its origin to some particular force controlled 

 by extracellular influences, each group of cells being made to manu- 

 facture 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 birthright the quality of producing from its par- 

 ticular 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 constitu- 

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

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

 stituents 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 pro- 

 cesses are as much, if not more, responsible for individuality of func- 

 tion 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 deter- 

 mine in a measure the character of the katabolic or alteration pro- 

 ducts that result from the natural activity of the cell protoplasm. In 

 other words, if this conception 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 fibres, etc., may all act 

 as modifying agents, but only to the degree of accelerating or inhibit- 

 ing the rhythmical process which travels along a certain definite chan- 



