DISTURBANCES OF GROWTH 249 



experiments, making each diet better in respect to the faulty factors than 

 the one which preceded it in the series, we can regulate the rate and extent 

 of growth of the several groups of animals and profoundly modify their 

 life histories. It is especially significant that a scries of diets may all 

 be of sufficiently high quality to permit of approximately normal growth 

 to the adult size, and the animals may present a good appearance during 

 growth, yet the slight faults in these diets may -lead to early loss of vitality, 

 early aging and inability to succeed in the nursing of the young. This 

 last function is of special importance in connection with the present dis- 

 cussion. 



Several situations may arise in such experiments. The mothers may 

 react unfavorably toward their young and destroy them soon after birth; 

 they may try to nurse them but because of inadequacy in the composition 

 or amount of milk secreted, fail to induce the proper rate of growth in 

 them. The evidence seems to support the view that long before the milk 

 supply falls off to a point sufficient to arrest growth in a suckling, the 

 quality of the milk has been sufficiently lowered to interfere with growth, 

 even though the energy requirements of the young are met. McCollum and 

 Simmonds(a) have studied this problem in the rat and have shown 

 that when the diet of a nursing female is faulty, with respect to any one 

 of several factors, the young will not grow as they should, and may even 

 die after an interval of malnutrition. It was found that after the growth 

 of a litter was suspended for a time by this method, they could be made 

 to respond with growth within forty-eight hours in many cases by cor- 

 recting the diet of the mother. In this manner they tested lack of suf- 

 ficient calcium, of fat-soluble A, of water-soluble B and of protein, as 

 the single and sole deficiency in tlie mother's diet, and in each case the 

 quality of the milk was seriously affected. 



This observation has an important bearing on the problem of the 

 diet most suitable for the human mother during lactation. It is food 

 for thought that in no instance with an animal as a subject has it been 

 possible to succeed in the nursing of young, on a diet consisting of cereal 

 grains, legume seeds, tubers, and muscle meats. The failure is even more 

 decided when a considerable amount of degerminated cereal products such 

 as wheat flour, corn meal and polished rice enter into the composition of 

 the food mixture. Is it not important that the nursing mother should 

 take regularly a diet of better quality than the type which is now so com- 

 monly adhered to, viz. : one consisting in great measure of bread made from 

 bolted flour, muscle cuts of meat and potato ? 



According to the investigations of the American Pediatric Society, ten 

 cases of scurvy out of a total of 356 were in breast-fed children. Beri- 

 beri is not infrequently seen in infants who nurse mothers who are suf- 

 fering from the disease. Rickets have been many times observed in chil- 

 dren who are breast fed. The causes of these diseases are well understood. 



