3;U C. M. JACKSON 



tvu weeks (sixty-seven days). At this time the ghind appears 

 to have reached its inaxhiiuiii normal vascularity; though no 

 actual measurements were made ujion later stages, and there is 

 naturally' some individual variation. 



In young animals held at maintenance, there is usually a 

 striking increase in the vascularity, the sections showing a marked 

 hj-peremic appearance. This is confirmed by the measurements 

 on two of the three cases in table 3, both showing an increase 

 of the vascular stroma to 13.4 per cent. The third case repre- 

 sents an unusual condition in which, on the other hand, there 

 appears to be a slight decrease to 8.8 per cent in the volume of 

 the vessels and associated stroma. 



In adult rats subjected to acute or chronic inanition the 

 hyperemia is usually even more conspicuous than in the younger 

 animals. This is confirmed by the measurements, showing for 

 the vascular stroma 16,7 per cent by volume for the case of acute 

 inanition and 17.5 per cent for the chronic inanition. These 

 may be considered as typical, though here also individual varia- 

 tions occur. 



In general, therefore, it appears that during inanition in the 

 pars anterior the parenchyma becomes reduced in relative vol- 

 ume, with corresponding increase in the vascular stroma. This 

 increase is due chiefly to a distention of the blood-vessels, giving 

 the sections a markedly hyperemic appearance. In a few cases, 

 especially in the young held at maintenance, there is also some 

 increase in the intercellular substance. 



6. Relative volumes of the nuclei and cyto-plasm of the parenchyma 



{table 3) 



In the parenchyma of the pars anterior, the nuclei form 34.1 

 per cent of the total cell volume in the newborn, decreasing to 

 24.1 per cent at three weeks and to 19.7 per cent at ten weeks 

 (sixty-seven days). The cytoplasm, of course, undergoes a 

 corresponding increase in relative volume (figs. 2 and 4). The 

 relations found in the specimen at ten weeks (St 47.5) appear 

 to be typical for adults, although no actual measurements were 



