3:^2 CM. JACKSON 



intermedia and nervosa becoming correspondingly larger. This 

 change is especially well marked in the rat held at maintenance 

 up to twelve weeks of age. 



c. Volumes of the lobes in adult rats subjected to acute and chronic 



inanition 



The 2 rats, S 27 and S 16, had been subjected to acute inani- 

 tion (water but no food given) for about ten days, with resultant 

 loss of about 30 per cent in body weight. The final body weights 

 are given in table 1. The pars anterior of the hypophysis in 

 these rats appears relatively somewhat larger than normal, the 

 pars intermedia somewhat smaller, the pars nervosa not much 

 changed in relative size (table 2 C). 



In the rat (M 12) subjected to chronic inanition (progressive 

 underfeeding for thirty-six days, with loss of 36 per cent in body 

 weight), the partes anterior and intermedia are smaller and the 

 pars nervosa larger than normal in relative size (table 2 D). 

 Thus the relative changes in the size of the lobes during chronic 

 inanition of the adult appear in general to resemble more nearly 

 the changes in the young during maintenance, which are some- 

 what different from those during acute inanition. The general 

 resistance of the pars nervosa during inanition recalls the similar 

 behavior of the closely related brain. 



d. Volumes of the lobes in rats refed after maintenance 



As seen in table 2 (E 1, E 2, E 3 and E 4), in the young rats 

 refed one-half week, one week, two weeks and four weeks, there 

 is a considerable individual variation in the relative size of the 

 parts (lobes) of the hypophysis. In general, however, there 

 appears a gradual return to the normal proportions, the pars 

 anterior increasing and the partes intermedia and nervosa de- 

 creasing in relative (percentage) volume. The exceptionally^ 

 small pars intermedia in the rat refed 4 weeks is probably an 

 individual variation. 



Two rats (table 2 E 5) were refed six or seven months after a 

 long period of maintenance, from the age of three weeks to five 



