l8o INANITION AND MALNUTRITION 



7.7 per cent less than that in full-fed controls of the same age, but 3.6 per cent 

 greater than the (calculated) initial brain weight. Aron ('n) noted that the 

 brain weight in puppies underfed for long periods is nearly equal to that in 

 the full-fed controls of the same age, but the lack of initial controls makes it 

 impossible to estimate the amount of growth in brain weight during the under- 

 feeding period. 



The changes in the brain weight of albino rats of different ages during 

 various degrees of underfeeding were studied by Jackson and coworkers, the 

 results being epitomized in Table 4. Jackson ('15a) observed practically no 

 change in the average brain weight of rats underfed for various periods begin- 

 ning at the age of 3 weeks or later. Stewart ('18), however, found that if the 

 underfeeding was begun at birth, allowing the body weight to increase slowly 

 from about 5 g. to 15 g. at 10 weeks of age, the brain weight increases 

 to 8 per cent above the normal for corresponding body weight. If the under- 

 feeding is more severe, retarding the body weight to only 10 g. the brain 

 weight increases to 60 per cent above the normal. In still severer inanition, 

 holding the body nearly constant at birth weight for about 16 days, Stewart 

 ('18a) found the brain weight 125 per cent above normal! Sugita ('18), in 

 nursing rats retarded 29-39 per cent in body weight by underfeeding 3-4 

 days, similarly found the brain 24 per cent above the standard for correspond- 

 ing body weight. Thus at this early age the brain shows a most remarkably 

 persistent growth tendency during inanition, which enables it (with certain 

 other organs) to grow at the expense of the remainder of the body. This 

 tendency is apparently not so strong in the fetus, however, since Barry ('20, 

 '21) found the brain only 12.5 per cent above normal weight in full term fetuses 

 which had been retarded 40 per cent in body weight by maternal underfeeding 

 during pregnancy. 



Stewart ('18a) also studied the weights of the parts of the brain in albino 

 rats held at birth weight (about 5 g.) for 5-18 days. The brain weight 

 in this series averages 114 per cent above normal. In another series, the body 

 weight was allowed to reach 10 g. at 3 weeks, and in these the brain weight 

 appears 33 per cent above normal for corresponding weight. The weights of 

 the various parts (cerebrum, cerebellum and brain stem) in general preserve 

 approximately the same relative weight as in normal individuals having the 

 same brain weight. The olfactory bulbs, however, appear hypertrophied in 

 the younger group. 



Data published by Trowbridge, Moulton and Haigh ('18) and by Moulton, 

 Trowbridge and Haigh ('22) indicate that the brain weight in underfed young 

 steers of various ages is both relatively and absolutely somewhat higher than 

 in full-fed controls of the same body weight. This would indicate that in 

 the bovine species, as in man and the rat, the growth of the brain during incom- 

 plete inanition appears relatively independent of the body as a whole. 



Recovery of Weight upon Refeeding. — In young albino rats amply refed 

 after underfeeding from 3 to 12 weeks of age, the weight of the brain was 

 observed to be normal by Stewart ('16). In rats underfed from birth for 

 arious periods and then refed, Jackson and Stewart ( '18, '19) found that the 



