122 EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 



renals gaming 26 per cent. Stewart (1918) , in chronic inanition in young rats, found 

 that the suprarenals gained 48 per cent in absolute weight, while Jackson (1915a) 

 found that the suprarenals lost during chronic inanition (26 per cent). In adult 

 rats there is very little or no loss of absolute weight of the suprarenals during either 

 acute or chronic inanition (Jackson, 1915). 



From these observations it would appear that the suprarenals in the rat have a 

 weak growth tendency during inanition in prenatal life and that it is still slight up to 

 16 days of age, reaching its maximum at a period between this time and 10 weeks, 

 and declining thereafter. 



Kidneys. — Jackson (1913) found the kidneys in the newborn rat to weigh 0.46 

 gram or 0.97 per cent of the body-weight. The Wistar norm (Donaldson, 1915) for 

 the kidneys in the newborn is 0.48 gram, or 0.97 per cent of the body-weight, 4.95 

 grams; in my normal newborns the weight of the kidneys is 0.46 gram or 0.94 per 

 cent of the body-weight, 4.92 grams. 



In my prenatal controls the weight of the kidneys forms 0.58, 0.63, 0.54, 0.71 

 and 0.70 per cent of the body-weight in Groups I to V respectively (computed from 

 table 5). Thus in the prenatal controls the relative weight of the kidneys is less 

 than that in the normal newborn rats. The difference decreases, however, from the 

 small to the larger rats (fetuses). Therefore it is evident that in the rat fetus 

 (from 2 to 4.1 grams) the kidneys are growing faster than the body as a whole. 



In my test rats the average weight of the kidneys forms 0.56, 0.67, 069, 0.67, 

 and 0.71 per cent of the body-weight in Groups I to V respectively (computed from 

 table 5). There is very little difference in the relative weight of the kidneys in the 

 test rats and the prenatal controls, but in neither have the kidneys reached the 

 relative (percentage) weight of the body which is normal at birth. In both, the 

 kidneys are growing faster than the body as a whole. 



The absolute weight of the kidney is variable. Comparing the test rats and the 

 prenatal controls (table 5), it is seen that in some groups the absolute weight is 

 higher in the test rats, in others in the prenatal controls. This makes the results 

 seem of questionable significance. Tins variability can not be attributed to errors 

 in technique, however, as the kidney is an organ easy to remove and clean. In the 

 test rats the absolute weight of the kidneys shows an average weight of 6 per cent 

 above the prenatal controls. 



This increase of 6 per cent in the absolute weight of the kidney during prenatal 

 inanition is not nearly so marked as that noted in young rats underfed for various 

 periods after birth. Stewart (table 6) found that the kidneys showed a gain of 90 

 per cent in absolute weight in rats kept at a birth-weight for an average of 16 days; 

 this gain was less marked if the underfeeding was prolonged to 3 weeks, being 21 per 

 cent (Stewart, 1918) . In rats underfed from birth to 10 weeks the kidneys showed a 

 gain of 38 per cent. In rats underfed from the age of 3 weeks to 10 weeks, however, 

 Jackson (1915a) found that the kidneys increased but 4 per cent; and in chronic 

 inanition in young rats, where the starvation was begun from 3 to 10 weeks after 



