92 GROWTH 



III. Prenatal Nutrition, and Condition at Birth 



Thus far our attention has been directed entirely to the nu- 

 tritional factors that are operative in the postnatal period. We 

 have, tacitly at least, assumed that all the individuals were alike 

 at birth, and that all were "normal." As a matter of fact, we are 

 perfectly certain that individuals do differ at birth, not only in 

 size, but also in other particulars that may have a determining 

 influence on their postnatal history. We may therefore properly 

 devote some attention to the nutritional factors that are opera- 

 tive in the antenatal stage, and consider especially the factors 

 that influence the weight and vigor of offspring at birth. One 

 question of both theoretical and practical interest is, what are 

 the controllable factors that influence the well-being of young 

 in the prenatal stage. 



Are we, for example, to assume that there is a direct relation 

 between the plane of nutrition of the mother and the weight 

 of the young. We will first consider the case that involves 

 merely more or less food, assuming that it is adequate in quality, 

 but in quantity may vary from gross overfeeding to a condition 

 of extreme underfeeding. The first possibility will receive very 

 brief consideration, for reliable data are not at hand on this 

 point. It is, however, the general opinion that females in ex- 

 cessively high condition do not produce as vigorous young as 

 those more moderately fed. The other phase of the question, 

 underfeeding, has received long and careful study, and the 

 data are by no means scanty, though unfortunately they also 

 are not concordant. 



Paton 44 attempted to answer the question in an experimental 

 way, and used guinea pigs as experimental animals. The first 

 point to be determined was whether well-fed guinea pigs pro- 

 duced the same weight of young regardless of the number in 

 the litter, and what was the proportion of the weight of young 

 to weight of the mother. 



