NUTRITION 259 



kind to those which we have discussed in the preceding pages. It has been clearly 

 shown by Fraser and Stanton (1911) that the disease known as " Beri-Beri" is due 

 to the exclusive feeding on rice which has had the pericarp and most of the under- 

 lying layer removed by " polishing." Fowls fed on such rice develop a polyneuritis 

 (inflammation and subsequent degeneration of peripheral nerves), which is similar 

 to that occurring in beri-beri, and can therefore be used to study the disease 

 experimentally. If the polishings be added to the white rice, the animals remain 

 healthy and those suffering from the disorder can be cured. As to the nature of 

 the protective substances whose absence entails the disease, it was found that 

 heating to 120 for two hours destroys them. They are soluble in slightly acid 91 

 per cent, alcohol. Further evidence on the nature of these substances has been 

 brought forward by Funk (1911, 1912), who has separated a substance from rice 

 polishings, and also from yeast, milk, ox-brain, and lime-juice, which, in very small 

 doses, 0-02 to O04 g. by the mouth, cures polyneuritis in fowls. Funk states 

 further that it has the properties of a pyrimidine base. Pyrimidine is : 



N CH 



HC? JH 



1 I 



N=CH 

 and is, together with iminazol : 



HC NH 



HC N 



the characteristic constituent of the nucleins. Marked improvement was, in fact, 

 obtained by giving certain substances related to the nucleins, such as thymus, 

 nucleic acid, guanosin, etc. Funk suggests the name " vitamines " for the class. 

 They are remarkably active ; a quantity containing only 0-4 mg. of nitrogen cures 

 a pigeon. An interesting point is that pigeons severely affected with poly- 

 neuritis recovered in six to twelve hours, and frequently seemed quite well after 

 three hours. It appears that the paralysis can have been due to a functional 

 disturbance only of the axis cylinders, although the medullary sheath was 

 degenerated. It is impossible that recovery of degenerated axones could take place 

 in so short a time. It appears that a normal medullary sheath is not absolutely 

 necessary for nerve conduction. It should be mentioned that the constitution 

 assigned by Funk to these " vitamines" is not generally accepted. We have seen 

 above (page 257) that the active substance in butter contains no nitrogen, so that 

 it seems probable that the substance investigated by Funk was not the active one, 

 and that this latter was present only in traces. Indeed, Funk himself appears to 

 have come to the conclusion later that this is the case, although he holds that the 

 active substance is of basic nature, and precipitated by phospho-tungstic acid. 

 The possibility has not yet been excluded, however, that the precipitate might 

 carry down the active material by adsorption. 



Scurvy has also been shown by Hoist and Frolich (1912) to be due to a 

 deficiency of some essential constituent in preserved foods, but present in all kinds 

 of fresh material, animal or vegetable. It will be remembered how Captain Cook, 

 in his second voyage, was successful in avoiding this disease, although the voyage 

 lasted 1,000 days. He says (1776, p. 405): "We came to few places where 

 either the art of man or nature did not afford some sort of refreshment or other, 

 either of the animal or vegetable kind. It was my first care to procure what 

 could be met with of either by every means in my power, and to oblige our people 

 to make use thereof, both by my example and authority ; but the benefits arising 

 from such refreshments soon became so obvious that I had little occasion to 

 employ either the one or the other." 



The extreme sensitiveness to the want of some particular substance in small 

 amount does not seem to be limited to the higher animals. Wildiers (1901) stated 

 that if a normal artificial culture medium is inoculated with yeast in too small an 

 amount, there is no growth, whereas, if the same quantity is added to sterilised 



