40 THE GERM-PLASM 



composed oi different kinds of chemical molecules. I shall call 

 these units the '■bearers of vitality^ (' Lebenstrager ") or ^ bio- 

 phors,' because they are the smallest units which exhibit the 

 primary vital forces, viz., assimilation a?id metabolism, growth, 

 a n d m u Itiplication by fission . 



As living protoplasm cannot be subjected to chemical analysis, 

 we cannot describe its chemical constitution more precisely ; but 

 what has so far been determined by the analysis of dead proto- 

 plasm certainly indicates that the albuminoids are not the only 

 bearers of vitality, as has generally been assumed, but that other 

 substances play a no less important part in living protoplasm, — 

 a fact which has been insisted on by Hoppe-Seyler and Bau- 

 mann. Besides albuminoids, compounds containing phosphorus, 

 such as lecithin and nuclein, which are not related chemically to 

 albumen, but enter into combination with it. are known to occur 

 in dead protoplasm ; and besides these, protoplasm also con- 

 tains cholesterin, which is probably a product of destructive 

 metabolism, and carbohydrates, such as glycogen, starch, inulin. 

 and dextrine, as well as compounds of potassium.* Although 

 we cannot at present guess from what chemical compounds in 

 living protoplasm these bodies have been derived, there can 

 be no doubt that ' a relation exists between them and the vital 

 processes' (Hoppe-Seyler), and that albumen, or different kinds 

 of albumen, do not alone bring about the vital processes, but 

 that several other substances, such as salts, and compounds 

 containing phosphorus, and more particularly water, are just as 

 essential : in short, life depends simply on the interaction of 

 molecules, differing chemically from one another, but defined 

 within certain limits. 



After long consideration, I have decided to designate such a 

 group of molecules on which the phenomena of life depend by 

 the special term ' biophor.' This seemed to be advisable, because 

 the various terms introduced previously by others were either 

 left too vague for these minute vital particles to be identified with 

 them, or if defined more exactly, were used with a different mean- 

 ing. It would certainly be a mistake to make use of a name 

 already introduced, in another sense from its original one. Her- 

 bert Spencer's f ' physiological units ' are similar to the biophors, 



* Cf. Hoppe-Seyler, ' Allgemeine Biologic,' Berlin, 1877, p. 75 (Part I. 

 of the ' Lehrbuch der physiologischen Chemie"). 



t Herbert Spencer, * Principles of Biology,' vol. i., p. 183. 



