EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 121 



In Group I the absolute weight of the pancreas in the test rats is less by 10 per 

 cent than in the prenatal controls; in Group II it is 2 per cent less; in Group III it is 

 20 per cent heavier; in Group IV, 16 per cent lighter; while in Group V it is 9 per 

 cent heavier. The average for all groups shows a deficit of 0.2 per cent in the test 

 rats. 



From the above it is seen that the weight of the pancreas is very variable. 

 Its low weight in one group is balanced by its high weight in another. Prenatal in- 

 anition probably has very little effect upon the relative weight of the pancreas, as 

 its average weight in the test rats is but 0.2 per cent below that in the prenatal 

 norms for the various groups. 



Suprarenals. — The weight of the suprarenals, according to the Wistar norm 

 (Donaldson, 1915) , is0.0017 gram for a rat of 5.1 grams, or 0.034 per cent of the body- 

 weight. Jackson (1913) gives the weight of the suprarenals in the newborn as 

 0.0019 gram (0.00188), or 0.039 per cent of the body-weight. In my normal new- 

 borns the weight of the suprarenals averages 0.0016 gram or 0.032 per cent of the 

 body-weight, 4.92 grams. 



The weight of the suprarenals in my prenatal controls forms 0.044, 0.050, 0.048, 

 0.049, and 0.045 per cent of the body-weight in Groups I to V, respectively (com- 

 puted from table 5). Thus the relative weight of the suprarenals in the prenatal 

 controls markedly exceeds that of the normal newborn rat. 



In my test rats the average weight of the suprarenals forms 0.026, 0.023, 0.022, 

 0.024, and 0.024 per cent of the body-weight in Groups I to V, respectively (com- 

 puted from table 5) . Thus it is evident that the relative weight of the suprarenals 

 in the test rats is less than one-half that in the prenatal controls. On the other hand, 

 however, their relative weight in the prenatal controls greatly exceeds their relative 

 weight at birth. Thus, in the prenatal norm fetuses studied (2.19 to 4.19 grams), 

 the suprarenals are relatively larger than at birth. They are probably still larger, 

 relatively, in earlier stages, although no data from their earlier size in the rat are 

 available. Jackson (1909) found that in the human fetus the suprarenals increase 

 rapidly to their maximum (relative volume) in the third fetal month, after which 

 they decrease steadily in relative size. 



In the test rats the suprarenals show an average weight 52 per cent below that 

 of the prenatal controls (table 5). The excessively weak growth-tendency of the 

 suprarenals during fetal inanition can not be explained as due to any peculiarity 

 ol their normal growth in rats at this time, for, as shown above, the prenatal con- 

 trols maintain a nearly constant relative (percentage) weight during this period. 



In postnatal inanition Stewart (1918a) found that in rats kept at birth-weight 

 for 16 days the suprarenals gained 5 per cent in absolute weight over newborn con- 

 trols, but with longer periods of starvation (underfed from birth to 3 weeks, body 

 weight 10 grams), he found that the suprarenals increased markedly in weight (60 

 and 114 per cent, respectively). 



Jackson (1915a) also found that the suprarenals manifested a marked growth 

 tendency in young rats underfed from the age of 3 weeks to 10 weeks, the supra- 



