160 



THE CELL AND PROTOPLASM 



important and indispensable, and if any 

 are missing there will be disturbed func- 

 tion and disease. Most of these wheels can 

 be manufactured by the cell itself from 

 other "raw materials" so that they can be 

 replaced when they are used up, even if 

 they are not contained in one's food. There 

 are, however, a few substances of medium 

 size, which our cells cannot put together 

 (a relatively small quantity) ; these must 

 be taken ready made or almost ready made 

 from our food. If the food does not contain 

 these substances and we are unable to re- 

 place a shortage in our own stores, there 

 will be disturbed function, a disease gener- 

 aDy called a "deficiency disease." These 

 are the substances we call vitamins. For 

 every single vitamin there will be a cor- 

 responding deficiency disease, an avitamin- 

 osis. 



In the last analysis all these vitamins 

 come from plants, for it does not matter 

 whether we eat the cabbage or the cow that 

 ate the cabbage. This simple fact involves 

 a point of the greatest philosophical im- 

 portance. If I look upon the cell as a 

 mechanism and upon the molecule as a 

 wheel of this mechanism, then by saying 

 that I take my vitamins from the plant I 

 say that there are two mechanisms, the 

 plant cell and my cells, whose parts, the 

 single wheels, are interchangeable. Two 

 mechanisms, whose parts are interchange- 

 able, cannot be very different. This is the 

 first scientific evidence for the great, funda- 

 mental chemical unity of living Nature. 

 There is no real difference between cab- 

 bages and kings. We are all recent leaves 

 on the old tree of life. 



Research has brought to light such a 

 wealth of observations on vitamins — their 

 nature, action, structure, distribution, 

 symptoms of deficiency, etc. — that it would 

 be a hopeless job to try to review this ma- 

 terial. For such a review I lack both time 

 and knowledge, and I could exhaust only 

 you and not my subject. So I will limit 

 myself to a review of the gradual develop- 

 ment of our general ideas concerning vita- 

 mins. 



To start somewhere I will start with the 



name, "Vitamin," and its implications. 

 "Vita" implies that these substances are 

 involved in the mystery of life; "amin" 

 means that they are chemicals known as 

 amines. Today there is no more mystery 

 and we know they are not amines^ that's 

 that. To be sure, life is still a mystery and 

 every substance involved in life is a mys- 

 tery, but in this connection there is no es- 

 sential difference between vitamins and 

 common salt. The latter looks much more 

 mysterious to me. 



There is another very important implica- 

 tion of the word "Vitamin." This word 

 suggests a quite specific, isolated, and 

 closely related group of substances, in some 

 way fundamentally different from all other 

 biological material. This is a most im- 

 portant point, for there has been much 

 speculation about "equilibria of hormones 

 and vitamins" and the like. If vitamins 

 are really a special sort of substance, this is 

 all right ; but if we denote by vitamins only 

 a group of substances which are related by 

 some secondary, accidental factor, then all 

 this is wrong. To make this clear: if I 

 classify together all biological substances 

 which have names beginning with P, for 

 instance, and give them a beautiful name, 

 say Pitamin, evidently any speculation 

 about the equilibrium of Pitamins with 

 hormones would be unjustified. 



In what way could Vitamins be different 

 from other substances: their appearance, 

 their structure, their biological action? In 

 appearance the vitamins are in no way dif- 

 ferent from other substances. There is no 

 uniformity in their chemical structure, 

 either. We find among vitamins the most 

 varied formations, like thiazines, alloxa- 

 zines, pyridines, carbohydrate derivatives, 

 phenanthrenes, etc. 



So our last hope is that we may find 

 some essential unity in the mode of action 

 of vitamins. When we speak of the mech- 

 anism of action of any biological investiga- 

 tion what do we mean? Physiology and 

 pharmacology have produced a host of sub- 

 stances with the most striking biological 

 activities, but we are ignorant about the 

 mechanism of these reactions. By mechan- 



