516 



NAOKI SUGITA 



TABLE 1— Concluded 



1 Under 10 grams net weight, over 10 grams gross weight given. 



2 Cut. 



^ Pregnant. 



■• Because of rigor mortis, this figure is not reliable. . 



average values are in fair accord with the reference table values 

 as shown in tables 3 and 4, corresponding respectively to tables 

 1 and 2. 



These latter values have been obtained by the use of the formu- 

 las devised by.Hatai and given in ''The Rat" (Donaldson, '15). 

 A comparison of the observed and calculated values shows that 

 in the case of Groups II-XV in table 3 and Groups II-XIII in 

 table 4, the agreement is close, and as these groups go up to 30 

 days of age or more they include the period in which there is any 

 important increase in the thickness of the cortex. After 30 days 

 of age the discrepancies which appear between the observed and 

 corftputed body weights and body and tail lengths are not sig- 

 nificant for the present investigation and may therefore be 

 neglected. 



