24-S SCIENCE PROGRESS 



prevention of scurvy and beri-beri, for not only do the various 

 vitamines possess different properties, but the omission of any 

 one of them brings about its own specific result. A striking 

 result of this specificity has been recently advanced by Funk. 

 He has shown that a certain diet may lead to cessation of 

 growth without the production of beri-beri or scurvy. Thus 

 the two chickens represented in fig. 19 are each two months 

 old, but the one fed on red rice has scarcely grown at all, and 

 has not shown the slightest sign of polyneuritis. Here the diet 

 contains anti-beri-beri and anti-scorbutic vitamines, but the 

 growth vitamine is absent. 



It may be asked in what way do these vitamines act. Do 

 they affect the absorption of food from the intestine ? Careful 

 investigation by Hopkins showed that in his experiments 

 involving the addition of small quantities of milk, not the 

 slightest difference in the percentage extent of absorption 

 could be discerned, whether the milk was added or not. The 

 rats without the milk absorbed as much food as those with, but 

 evidently the food in the former case was not being properly 

 applied within the body. 



It is also not a question of appetite. The rats without the 

 milk ate as voraciously as the others, and it was only when 

 the rats began to lose weight that the amount of food consumed 

 began to grow less. In many cases it was conclusively demon- 

 strated that the animals on the milk-free diet continued to eat 

 and absorb a quantity containing an ample supply both of 

 protein and energy for the continuance of growth at a time 

 when their growth had wholly ceased. The loss of appetite 

 followed the cessation of growth and did not precede it. 



The minuteness of the quantities of these vitamines which 

 are requisite to maintain normal processes of life suggest that 

 they must have something to do with the production of some 

 of the essential hormones, internal secretions, enzymes, etc., in 

 the animal organism. Careful post-mortem examination of 

 polyneuritic pigeons by Casimir Funk has shown that this 

 condition is associated with an extreme atrophy of the thymus, 

 which suggests that the vitamine in rice husk has to do with 

 the stimulation of this organ, which we know is largest, and 

 evidently exerts its chief functions, during the period of 

 growth. 



It eems probable that other vital processes may also be 



