Watson, Weight of the Nervous System. 5 1 9 



of young, etc. The general features of the table are clear, but 

 one point is worthy of note. Immediately after the birth of 

 the young, the mated rats are much heavier than the unmated.^ 

 The mated animals, during pregnancy, seem to have the power 

 of storing up in some way (fat?) the products obtained from 



TABLE I. 



Showing the average body weight, at the ages given, of the two mated 

 and the two unmated rats of Group C.^ 



*The above average for the mated rats is based upon the record of two indi- 

 viduals until the 233rd day ; thereafter, upon one. 



''MiNOT : op. cit. There is one difference between the guinea pig and 

 the rat as regards the loss of weight during lactation. The loss in the guinea 

 pig is most rapid during the first three or four days after parturition. Just the 



