398 THE BIOCHEMISTRY OF B VITAMINS 



deficient in each of several B vitamins by means of techniques similar 

 to those used with higher animals. Certain insecticides such as "Gam- 

 mexane" (hexachlorocyclohexane) may function to produce conditioned 

 deficiencies in some other insects by antagonizing vitamin activity, 20 and 

 it is interesting to reflect on the possible action of certain "weed killers" 

 by a similar mechanism. In general there seems to be little present inter- 

 est in this general field of endeavor, however, despite the many intriguing 

 possibilities that exist for improving the growth of both plants and 

 economically important lower animals, and the destruction of undesirable 

 members of both kingdoms by vitamin analogues. 



B Vitamin Deficiencies in the Higher Animals 



Introduction. While the roles of thiamine and nicotinic acid in the 

 etiology of beriberi and pellagra have been recognized for only a rela- 

 tively few years, these two important B avitaminoses have been recog- 

 nized as human afflictions for centuries. Beriberi was well known and is 

 clearly described in the literature of the 7th century in China, although its 

 spread to Japan was not apparent until a thousand years later, possibly 

 as a result of the introduction of polished rice into the Japanese diet at 

 that time. Descriptions of pellagra apparently do not occur before the 

 early part of the 18th century, although the affliction probably occurred 

 before this time. It is difficult to estimate the full effect of these two 

 diseases during the course of history. In the Philippine Islands as late 

 as 1947 the mortality rate due to beriberi was 132 per 100,000 popula- 

 tion, being second only to pulmonary tuberculosis. 18 In the Japanese 

 navy prior to Takaki's work the incidence was 23 per cent. 19 Just as beri- 

 beri is endemic in the Orient, so pellagra has been in many other areas 

 of the world, including the southern United States. In 1941 in this country 

 there were 1868 deaths from this disease reported. 20 All these figures 

 constitute only that small part of the total cases that terminated fatally, 

 and reflect only those deaths reported to the authorities and known to be 

 due to this cause. Moreover, the indirect effects of this malnutrition un- 

 doubtedly resulted in a far higher mortality than the avitaminosis itself. 

 At present, with the technical ability available to eradicate these and 

 other avitaminoses, the overall picture is changing only slowly, because 

 of the enormous problems involved in practical implementation of the 

 prophylaxis and therapy in most of the populations where these diseases 

 occur. 21 



The discussion of the avitaminoses which follows must of necessity be 

 from the standpoint of a consideration of undesirable afflictions that have 

 no place in a well regulated society. It is indeed difficult to picture disease 

 as serving any good purpose, and yet in some instances we find reports of 



