EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 105 



corresponding to the smaller size of their heads and extremities. The difference in 

 the size of the trunk, however, is slight, as evidenced by the fact that its absolute 

 weight in the test rats shows an average loss of but 1.6 per cent. This loss of weight 

 in the trunk compensates for the larger head and extremities in the tests. 



Consequently it appears that in prenatal retardation by inanition there is a 

 slight increase in the weight of the fore limbs especially in the smaller rats, a more 

 marked increase in the hind limbs, and a slight decrease in the weight of the trunk. 

 In postnatal starvation in young rats held at a constant body-weight there was very 

 little change in the weights of the trunk and extremities as compared with controls 

 of the same body-weight. In general, there was a slight increase in the weight 

 of the head, counterbalanced by a slight decrease in the weight of the trunk and 

 extremities (Jackson, 1915a; Stewart, 1918). During inanition in adult rats, both 

 the head and extremities appear to increase in relative weight, while the trunk 

 decreases (Jackson, 1915; see table 6). 



Integument. — In my normal newborns the average weight of the integument is 

 0.794 gram (16.1 per cent of body-weight, 4.92 grams). Stewart (1918a), in new- 

 born litters from the same colony, found the weight of the integument to be 0.754 

 gram (15 per cent of the body-weight, 5.03 grams). These values are slightly 

 lower than that given by Jackson and Lowrey (1912), which was 0.930 gram (19.8 

 per cent of body-weight). The difference is probably due to a variation in tech- 

 nique, as it is difficult to remove the skin with uniformity. 



In my prenatal controls the weight of the integument forms 11.0, 12.8, 13.4, 

 13.9, and 14.2 per cent of the body-weight in Groups I to V, respectively (computed 

 from table 5). Thus it is evident that the weight of the normal integument is 

 relatively less in the fetus, increasing progressively up to birth. 



In my test rats the weight of the integument forms 12.4, 13.6, 15.3, 15.3, and 

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

 table 5). The integument in the test rats thus forms a relatively higher percentage 

 of the body-weight (in all the groups) than in the prenatal controls. 



The absolute weight (see table 5) of the integument in the test rats exceeds that 

 of the prenatal controls by 18 per cent in Group I, 6.4 per cent in Group II, 14.6 per 

 cent in Group III, 10 pf r cent in Group IV, and 3 per cent in Group V. The average 

 increase in all the groups is 10.4 per cent. Although this increase in weight is 

 irregular, it has a downward trend from Group I to Group V and shows that the 

 nearer the prenatal controls and test rats approach their normal birth-weight, the 

 less is the difference in the relative (percentage) and absolute weights ol their 

 integuments. This increase may be due to the longer interval the test rats 

 remained in utero as compared with the prenatal controls, or to the fact that the skin 

 has a stronger growth tendency at this time as compared with some of the other 

 parts of the body. It is interesting to note (see table 6) that Stewart (1918) found 

 the integument to remain at a constant weight in rats starved from birth to 3 weeks 

 of age, while in older rats starved for longer or shorter periods the loss in weight of 

 the integument was quite marked. In a younger series kept at a maintenance diet 



