SOME FACTORS AFFECTING FETAL DEVELOPMENT A 
BY JOHN M. EVVARD. ## 
That the nourishment of the mother during the period of gestation 
should affect th,e weight, vigor, general relative size, bone and skin (with 
covering) of the offspring is quite evident from the results of some 
recent experimental studies made by ms. Dr. A. W. Dox and S. C. 
Guernsey of the Chemical Section are working upon the chemistry of 
this problem -in co-operation with the writer. Our work is being carried 
on with both sheep and swine in order that we may get a double set of 
records upon different species of animals. 
How may the offspring be affected? This is a very important ques- 
tion. In the first place the new-born may possibly be affected through 
the dam, depending upon her nutrition, age, weight, stature (special 
emphasis being laid upon the conjugal diameter of the pelvis) , health, 
shortening or lengthening of the period of gestation (from whatever 
cause), the number of preceding pregnacies, breeding and exercise (or 
confinement) . Secondly, the sire may have some influence dpending upon 
his age, weight, stature, breeding and general health. Thirdly, through 
the character of the offspring themselves, depending upon their number 
and sex. The number may possibly be influenced by the nutrition of 
the dam during the breeding season, as some of our studies tend to show, 
, but we will reserve this for a later report. There may be a general 
commingling of various factors in determining the character of the result- 
ing offspring. ■ 
We are most interested in the nutrition of the dam during the preg- 
nancy period, and its effect upon the developing fetus. Are there any 
specific food constituents or elements such as protein, carbohydrates, fats, 
calcium, phosphorus, water, or other 'specific materials which are instru- 
mental in affecting development in utero, or, are the changes due to an 
abundance (or absence) of all of the needed food elements or to a happy 
combination in definite ratios (depending upon the environment) of 
many of the food elements ? Will any one food stuff have a more marked 
influence than anotheF? - Many 'problems are •' involved in such a study. 
