VITAMIN A 291 



strikingly that a proportion of vitamin A in the food sufficient to sup- 

 port normal growth and maintain every appearance of good health, 

 for a long time at least, may still be insufficient to meet the added 

 nutritive demands of successful reproduction and lactation. 



"Along with the failure to reproduce successfully there usually also 

 appeared in early adult life an increased susceptibility to infection and 

 particularly a tendency to break down with lung disease at an age 

 corresponding to that at which pulmonary tuberculosis so often de- 

 velops in young men and women. The bacillus involved is different ; but 

 the close parallelism of increased susceptibility of the lung to infection 

 at this stage of the life history appears very significant, especially in 

 view of the fact recorded in another paper from this laboratory that 

 the vitamin-A-content of lung tissue varies with that of the food. 

 Especially noteworthy was the repeated observation of young females 

 growing normally and presenting every appearance of good health 

 throughout youth on a diet low in vitamin A, but failing utterly to 

 succeed in the rearing of a second generation, and showing a strong 

 tendency to break down in health at an age at which they should have 

 been in the prime of life." 



Batchelder (1929) studied further the effects of successive dimi- 

 nutions of vitamin A in the food on the nutrition and vitality of 

 all ages in experiments in which rats were fed diets containing 8.22, 

 4.11, 2.06, 1.03, 0.51, and 0.00 per cent butter fat. The diets highest 

 and lowest in butterfat were identical with the Sherman and MacLeod 

 diets in vitamin A content. The vitamin A content of the diets de- 

 creased practically in proportion to the amount of butterfat present, 

 the vitamin A contents of the other constituents of the diet being shown 

 to be insignificant. Each of the original animals entered the experiment 

 with a bodily store of vitamin. 



The only difference here established between rats on 8.22 per cent 

 butterfat and rats on one-half that amount, was that the offspring of 

 the former had larger stores of vitamin A in their bodies. 



A lower weight at all ages was observed for each decrease in but- 

 terfat below 4.11 per cent. A significant difference in the weight of 

 young at 28 days was found in rats on diets containing between 4.11 

 and 2.06 per cent butterfat; in the number of young reared by rats 

 on diets containing below 2.06 per cent ; and of young born among 

 rats on diets containing below 1.03 per cent butterfat. Rate of 

 growth, duration of reproductive life, and longevity also were de- 

 creased in rats on diets containing significantly below 1.03 per cent of 

 butterfat. 



