94 THE VITAMINS 



for milk (about 10 cubic centimeters daily being required for satis- 

 factory growth in rats). Fresh prunes were comparatively rich (5 

 grams daily promoting rapid growth), apples and pears less rich, and 

 grape juice markedly deficient in vitamin B. Spohn (personal com- 

 munication) has found the vitamin B content of two varieties of apples 

 to vary by about 15 per cent. Miller, working in Hawaii, has found 

 pineapples, fresh and canned (1924), to compare favorably with 

 citrus fruits and the native papaya (1926) to be only about half as 

 rich in its vitamin B content. The avocado was reported by Santos 

 (1922) to be about as rich in vitamin B as togi or okra, 0.5 grams of 

 dried material daily being sufficient in curative tests for rats. In pre- 

 liminary studies Tilt (personal communication) reports 1.4 grams 

 daily of fresh Florida-grown avocado sufficient to maintain the weight 

 of rats for an 8 weeks experimental period. According to Eddy and 

 Kellogg (1927) the banana has about the same vitamin B value as 

 tomato juice. From the limited data available apples, peaches, and 

 grapes appear to be similar to bananas as sources of vitamin B. 



So far few attempts have been made to determine the relative 

 richness of vitamins B and G in fruits. Eddy (1928a) has shown 

 that the banana is relatively richer in the heat-stable vitamin G than 

 in the antineuritic vitamin B. 



Nuts. — Cajori (1920), working with rats which consumed 6 to 8 

 grams of total food per day, found that if almond, English walnut, 

 black walnut, chestnut, Brazil nut, or pecan were included in the 

 ration to the extent of 1 to 2 grams per day, the nut sufficed as 

 sole source of the B vitamin. This would imply that nuts are nearly 

 but not quite as rich in vitamin B as are the whole cereals, the dry 

 legumes, or the solids of milk or eggs. Salmon and Livingston (1925) 

 tested pecans for vitamin B with pigeons and rats. The minimum 

 protective dose against polyneuritis was from 3 to 3.4 grams daily, 

 representing from 17 to 20 per cent of the total ration. Rats de- 

 clining on a ration lacking in vitamin B were able to maintain their 

 weight when 10 per cent of pecans was added to the basal ration, 

 but concentrations of 20, 40 or even 60 per cent failed to produce 

 normal growth. The rats on the 60 per cent ration were consuming 

 about 2 grams of pecans a day. This would seem to indicate that 

 the values reported by Cajori were perhaps too high, as were most 

 of the data obtained before the necessity was realized of preventing 

 access of the experimental rats to their excreta.^ 



^ It should be noted, however, that some laboratories used cages with raised screen floors 

 to prevent access to excreta in vitamin work, on the general principle of permitting the test 

 animal to eat nothing but the food, before the necessity for this had been explicitly demon- 

 strated by Steenbock in his work upon vitamin B. 



