64 



GROWTH IN TOTAL BODY WEIGHT 



At about the 13th day after insemination the fetus is large 

 enough to be directly weighed and from this date to birth the 

 growth has been followed. 



In a series of 38 females, each of which had already born one 

 litter, Stotsenburg (MS '15) has observed exactly the time of 



Fetus of albino rat 



Weight in grams 



13 



14 



15 



16 



17 



18 



19 



20 21 22 Days 



Chart 1 shows the course of fetal growth from the 13th to the 22nd day 

 gestation. Stotsenburg (MS '15). The data are given in table 46. 



insemination and then weighed the fetuses at the ages given in 

 table 46. Before weighing the membranes were removed and in 

 some instances the crown-rump length was measured (table 

 47) . The graph representing the growth before birth from the 

 13th day on is given in chart 1, the interval used for one day be- 

 ing two-fifths of that used for one gram. 



