DoNALDSON-ScHOEMAKER, Nevvous System of Frogs. 1 29 



tion is based on the examination of twenty four specimens (pre- 

 served in 70% alcohol after killing by formalin) of esculenta 

 and temporaria which we obtained from Zurich, Switzerland, for 

 the purpose of comparison with our own species, and also from 

 the study of the pictures of the brain and cord of the European 

 frogs as they appear in the books, to say nothing of the evi- 

 dence based on analogy with our own forms. 



No explanation of this peculiarity in Fubini's tables is evi- 

 dent, so that the point requires further investigation. 



Of course Fubini made no corrections for the probable loss 

 of body weight in the frogs taken in the spring and this is im- 

 portant, as he expressly states that the observations on R. tem- 

 poraria were made during the breeding season. 



The chief source of error however, and the one which nul- 

 lifies his principal conclusion, lies in his failure to appreciate the 

 effect of the increase in the body weight of the frog on the 

 proportional value of the central nervous system or the brain. 

 In the four tables which he gives, the average body weight for 

 each of the four series of females was heavier, and often much 

 heavier, than the averages for the corresponding series of males. 



This is shown by his records which we here quote in tab- 

 ular form : 



In the case of the unopened frogs, Nos. i and 3, the ova 

 must in, large measure account for the excessive weight of the 

 females and hence these records are useless for our present pur- 

 pose. The eviscerated series Nos. 2 and 4, however, still show 

 the average weight of the females to be the greater by 29% 

 and 40 % , respectively. 



