EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 125 



the ovaries lose 27 per cent (Jackson, 1915a) . In longer periods of inanition Stewart 

 (1918) found a gain of 17 per cent in the weight of the ovaries, while Jackson (1915a) 

 found a loss of 54 per cent. It should be remarked, however, that Jackson began 

 the underfeeding at 10 weeks instead of at 3 weeks, as in Stewart's series. 



From these data it may be concluded that in prenatal life and up to a few days 

 after birth, the growth tendency in the ovary during inanition is very slight; but 

 that it soon reaches a maximum at a period between 2 and 3 weeks of age, declining 

 later. 



Thyroid. — The Wistar norm (Donaldson, 1915) for the weight of the thyroid 

 gland is 0.00145 gram, or 0.027 per cent of the body-weight, 5.1 grams. Jackson 

 (1913) gives the weight of the thyroid as 0.0012 gram, body-weight 5.1 grams. 

 In my normal newborn series the thyroid weighed 0.0011 gram, or 0.022 per cent 

 of the body-weight, 4.92 grams. 



In my prenatal controls the weight of the thyroid forms 0.040, 0.030, 0.032, 

 0.029, and 0.029 per cent of the body-weight in Groups I to V, respectively (com- 

 puted from table 5) . Thus in the prenatal controls the thyroid forms a relatively 

 higher percentage of the body-weight than in the normal newborn. Since the 

 relative weight of the thyroid decreases as the birth-weight is approached, it is 

 evident that the body as a whole is growing faster than the thyroid. 



In my test rats the thyroid forms 0.024, 0.020, 0.023, 0.021, and 0.016 per cent 

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

 in the test rats the thyroid has about the same relative weight as in the normal new- 

 born rat and a lower relative weight than in the prenatal controls. 



That the thyroid has been inhibited in its growth in the test rats is evident from a 

 comparison of the absolute weights (table 5) . The absolute weight of the thyroid in 

 the test rats is 33, 28, 11, 29, and 45 per cent less than that in the prenatal controls 

 in Groups I to V, respectively. Thus, the absolute weight of the thyroid is lower 

 in all the groups, the average being 29 per cent. 



In postnatal inanition the thyroid exhibits a tendency to gain slightly in 

 weight in rats held at maintenance from birth to 16 days, or starved from birth to 3 

 weeks, or from birth to 10 weeks (Stewart, 1918, 1918a). In longer periods of 

 starvation the thyroid loses quite markedly (Jackson, 1915a; Stewart, 1918). 



In adult rats, during acute inanition, the thyroid suffers very little or no loss in 



weight, while during chronic inanition it loses relatively less than the body as a 



whole (Jackson, 1915). 



DISCUSSION. 



A comparison of the similarities and differences in the growth of the various 

 organs and systems in both prenatal and postnatal inanition is so well shown in 

 table 6 that a detailed discussion is deemed unnecessary. However, special 

 attention will be called to certain points. 



In the systems (see table 6) the "remainder" is constantly above normal in 

 weight in prenatal inanition, while in postnatal inanition it shows a definite loss at 

 various periods throughout the life of the rat. 



