558 Dr. Arthur Harden [April 28, 



is not essential, and no definite relation can be shown to exist 

 between the two. Vitamin C is either absent from seeds or only 

 present in them in very minute amount, but appears when the seed 

 germinates and before any green parts are formed. Nothing is, 

 however, known of the inactive pro-vitamin or of the process by 

 which it is rendered active. 



Concerning the origin of Vitamin B a considerable amount of 

 discussion has taken place. Its presence in a large proportion in 

 yeast points to the probability that it can be produced without the 

 intervention of light, and both in America and in this country it has 

 been found that yeast can actually produce the vitamin when grown 

 in a " synthetic medium " comprising only substances of known com- 

 position and free from the vitamin in question. Recently, however, 

 Eijkman, in Holland, has obtained a contrary result, so that at 

 the moment this remains an open question. 



The animal organism appears to be unable, in normal circum- 

 stances, to produce any of these principles for itself, and hence the 

 amounts found in animal products depend ultimately on the diet of 

 the animal. This opens up, among many other problems, the im- 

 portant question of the vitaminic properties of milk, and there seems 

 to be no doubt, from experimental work, both here and in America, 

 that these properties are profoundly affected by the diet of the cow. 

 Milk obtained in winter when the animals are stall-fed has been 

 shown to be markedly deficient in Vitamin A, and there is also great 

 danger of a deficiency of Vitamin C. One of the pressing require- 

 ments of the moment is the careful quantitative examination of 

 foodstuffs available for the feeding of cattle, so that a rational system 

 of winter feeding can be adopted which will produce milk as good as 

 that given in summer. Such an examination would seem naturally 

 to fall within the purview of the Board of Agriculture. 



The evil results of a deficiency of Vitamins B and C, especially 

 in the diet of children, are well known — beri-beri and scurvy, latent 

 or patent — but the effect of a lack of Vitamin A is not so well 

 recognised or so universally acknowledged. One school considers 

 that a deficiency of this vitamin is at least a prominent factor in the 

 causation, if not, as they formerly held, the sole cause of rickets. 

 Others consider rickets to be a disease brought on by non-hygienic 

 surroundings, lack of fresh air and exercise, etc. The latest experi- 

 mental results show that rickets (in rats) can be produced infallibly 

 by dietetic changes, but that the lack of Vitamin A does not of itself 

 lead to the disease unless at the same time the diet is faulty as regards 

 the supply of calcium or phosphorus. This faulty mineral supply 

 does not usually lead to true rickets if sufficient Vitamin A be present, 

 although the bone formation under these circumstances is not quite 

 normal. This explains the well-known curative effect of cod-liver 

 oil in rickets. So marked is the effect of this remedy, that McCollum, 

 not appreciating the relatively enormous concentration of Vitamin A 



