PART II, SERIES 2. ON THE PARTS OP THE SKELETON 

 IN THE CAPTIVE GRAYS 



Before discussing the effects of captivity, as just presented 

 in series 1, the observations on the parts of the skeleton, 

 series 2, will be considered. 



The rats used for this series were from the same genera- 

 tion groups as those examined in series 1. They were, how- 

 ever, different individuals, and the data do not become avail- 

 able until G 4 . 



With two exceptions, the averages used were based on five 

 individuals in each sex group in each generation. The dis- 

 sections were all by Miss Ruth Meeser. Using this material, 

 the following determinations have been made: 1) the weight; 

 2) the length, and, 3) the percentage of water for the cranium, 

 mandible, humerus, and femur. 



The purpose of these observations was to determine 

 whether there were any progressive changes taking place in 

 the bones of the captive Grays between G 4 and G 10 and also 

 to determine whether such changes indicated a shift toward 

 the values for the Albino. In the absence of corresponding 

 observations on the wild strain, the relations of the captive 

 Grays to this strain could not be determined. 



The relations found have proved to be so similar in all the 

 four parts of the skeleton examined that the data for the 

 femur, which are typical, will alone be presented here. 



The standard values used for the several base lines are 

 from reference tables 131, 128, and 163 for the Albino. The 

 computed deviations are given in table 25 and plotted in 

 chart 22. 



Examination of the graphs shows that the deviations in 

 the length of the femur are slight and those that occur are 

 mainly retardations in response to unfavorable conditions. 

 The deviations in weight are, however, large, and the retarda- 



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MEMOIR 14 



