GROWTH AND STRUCTURE OF HYPOriiYSIS IN RAT 331 



TABI.E 2-Conclude(l 



BODY 

 WEIGHT 



HYPO- 

 PHYSIS 

 WEIGHT 



VOLUME OF 

 GLAND 



VOLUMK OF 

 LOBES 



PERCENTAGE FORMED BY 



E 3. Rats refed two weeks after maintenance from three to twelve weeks of age 



E 4- Rats refed four weeks after maintenance from three to twelve weeks of age 



St 12.47 



f 



109 



106.5 



0.0082 



0.002608 



0.002608 



4.5 8.8 



E 5. Rats refed six or seven monlM after maintenance to age of about five months 



therefore possible that further data would modify my provisional 

 conclusion that the larger gland in the female is due to a larger 

 anterior lobe. 



The pars intermedia averages somewhat higher in the males 

 than might be expected according to the theory above mentioned 

 (that the sexual difference in hypophysis weight is due to differ- 

 ence in the anterior lobe alone), but this is probably due to the 

 unusual individual variations, which table 2 shows to occur in 

 the pars intermedia. 



It may be noted that in the one rat (J 1.7) killed at the end 

 of pregnancy, the expected hypertrophy of the gland apparently 

 failed to occur, and no marked change is evident in the relative 

 size of the three parts (lobes). The other females used were all 

 virgins. 



h. Volumes of the lobes in young rats held at maintenance 



As shown in table 2 B, in the 3 young rats held at maintenance 

 (nearly constant body weight) from three to ten or twelve weeks, 

 the pars anterior has been reduced in relative volume, the partes 



