Donaldson, American and European Frogs. 



129 



Although this is probably not the best method, it was uniformly 

 applied in the case of all three series, so that the results are at 

 least comparable, though the absolute values for the percentage 

 of water may be open to question, until it has been shown that this 

 material dried in vacuo, gives similar results. 



Material examined. — -The specimens of R. pipiens were 12 in 

 number (10 males and 2 females) ranging in body weight from 

 1 1 .6-47 grams. They were taken in the neighborhood of Chicago 

 in the month of August, and examined between the twenty-third 

 and thirty-first of August. For the data which are presented 

 in Table 7 I am indebted to Dr. S. Hatai. 



TABLE 7. 

 Data on R. pipiens. 



Ratio of 

 Brain Weight 



TO 



Cord Weight. 



2.64 

 2.26 

 2. 10 

 2.17 

 2.25 

 2.22 

 2.52 

 2.18 

 2.28 

 2.26 

 2.42 

 2.17 



Percentage of 

 Water. 



Brain. 



85 



86 



84 



Sp. C. 



The specimens of R. esculenta were eleven in number (3 males 

 and (8 females) ranging in body weight from 12.4-45.03 grams. 

 They were taken near Zurich on July 31, and were examined ' 

 between August i and 5. The data are given in Table 8. 



The specimens of Rana temporaria (fusca) were twelve in num- 

 ber (8 males and 4 females) ranging in body weights from 14.05- 

 32.81 grams. They were taken near Liverpool shortly before 

 July II, and were examined July 11 and 12. The data are given 

 in Table 9. 



In all the foregoing series there is considerable individual varia- 

 tion in the characters observed, and so for the purposes of com- 

 parison, the complete tables have been condensed by taking the 



