328 



E. R. HOSKINS 



TABLE 10 



Thyroid-fed albino rats. Average percentage deviation of organ weight from that 

 of the control rats, compared according to Donaldson' s method ('The Rat,' Donald- 

 son '15). 



Brain 



Eyeballs 



Heart 



Liver 



Spleen 



Alimentary canal 



Suprarenals 



Kidneys 



Ovaries 



Testes 



Hypophysis 



OLDER GROUPS 



Females 



per cent 



- 3.6 

 + 0.5 

 +24.6 

 +26.7 

 +41.3 

 + 12.1 

 + 16.1 

 +46.3 



- 3.2 



-11.5 



Males 



■per cent 



+ 0.1 



- 0.1 

 +36.0 

 +24.6 

 +86.0 

 + 11.8 

 +38.1 

 +44.4 



- 0.2 

 +21.3 



YOUNGER GROUPS 



Females 



ptr cent 



+ 0.5 

 + 6.8 

 + 16.7 

 +30.5 

 + 15.0 



+ 14.5 

 +33.0 



- 3.5 



- 8.8 



Males 



per cent 



- 5.5 



- 8.5 

 + 15.4 

 + 6.4 

 + 6.4 



+36.4 

 +40.4 



+ 9.8 

 + 18.0 



11. Lungs {tables 4 io 9) 



a. Controls. The weights of the lungs in the older rats are 

 considerably heavier than those of Donaldson's tables, owing 

 to the prevalence of pulmonary infection in my older rats. The 

 younger rats are in close agreement with the -Wistar tables. 



h. Thyroid groups. On account of the great variation due 

 to the frequency of lung infection (especially in the older ani- 

 mals), no conclusions can be drawn from the apparent changes 

 in the weight of the lungs in the thyroid-fed groups. 



c. Thymus, hypophysis, and pineal groups. There are no 

 differences that are of significance in the weights of the lungs 

 in these groups. 



12. Liver {tables 4 to 10) 



a. Controls. In absolute weight, the liver averaged some- 

 what below the corresponding figures in Donaldson's Wistar 

 tables, excepting in the younger males. Jackson ('13) also 

 found the liver normally considerably below the theoretical 

 curve derived by Hatai ('13). The liver is known to vary greatly 

 under different circumstances, however, and is considerably 



