EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 113 



after birth, but also present up to adult life. It should be noted that this growth 

 tendency persists for a longer time in the cord than in the brain, probably due to the 

 fact that the brain normally completes its postnatal growth at a relatively earlier 

 age than does the cord. 



Why the cord should lose while the brain gains in weight during fetal inanition 

 is difficult to explain. So far as their normal growth tendency during the fetal 

 period is concerned, both appear to be decreasing in about the same relative pro- 

 portion, judging from a comparison of their prenatal growth norms. 



Eyeballs. — The eyeballs in my normal newborns weigh 0.025 gram and form 

 0.50 per cent of the body-weight, 4.92 grams. In Stewart's (1918a) newborn they 

 weighed 0.0235 gram and formed 0.47 per cent of the body- weight, 5.03 grams. Jack- 

 son (1913) gives the weight of the eyeballs in the newborn as 0.025 gram and 0.53 

 per cent of the body-weight. 



In my prenatal controls the eyeballs form 0.38, 0.42, 0.42, 0.38, and 0.37 per 

 cent of the body- weight in Groups I to V, respectively (computed from table 5) . 

 Compared with the normal newborn rat, the relative weight of the eyeballs is much 

 lower in the prenatal controls. 



In my test rats the eyeballs form 0.57, 0.52, 0.50, 0.48, and 0.46 per cent of the 

 body-weight in Groups I to V, respectively (computed from table 5). Thus it is 

 evident that the eyeballs in the test rats have a much higher relative weight than in 

 the prenatal controls. In the test rats the relative weight of the eyeballs is about 

 the same as that of the normal newborn. (In the smaller rats it is slightly higher.) 



The absolute weight of the eyeballs is markedly higher in the test rats than in 

 the controls in all the groups (table 5), being most pronounced in Group I (the 

 smallest rats), in which the average absolute weight of the eyeballs of the test rats 

 is 56 per cent above that in the prenatal controls. It is interesting to not( that, in 

 the range of their weights, in Group I the heaviest eyeballs in the prenatal control 

 just equal the lightest in the test rats. In the other groups the eyeballs in the test 

 rats show an increase in absolute weight above the prenatal controls of over 20 per 

 cent. The average total excess of the absolute weight of the eyeballs in the test rats 

 above that in the prenatal controls is 31.4 per cent. 



These results are quite in accord with those obtained in postnatal inanition, 

 although less marked. In postnatal inanition the strongest growth capacity of the 

 eyeball is exhibited in newborns underfed from birth to an average of 16 days 

 (Stewart, 1918a), the increase being 146 per cent (table 6). This growth capacity 

 of the eyeball during inanition then decreases somewhat, but rises again in older rats 

 and persists in animals underfed up to 1 year of age. In older rats (adults), in both 

 acute and chronic inanition, the eyeballs lose slightly in weight according to Jackson 

 (1915). He suggests that this remarkable capacity of the eyeball to continue its 

 growth during inanition may be due to its power to absorb water, which makes up so 

 large a proportion of its composition. 



Thymus. — In my normal newborns, the average weight of the thymus is 0.0070 

 gram or 0.14 per cent of the body-weight, 4.92 grams. Stewart (1918a) gives the 



