114 Journal of Comparative Neurology. 



this time still in a condition to react like those taken earlier in 

 the season. 



A third series of five frogs was tested in September, all the 

 conditions being the same as in the earlier observations. The 

 record is again given at three and four day intervals. 



In this series, Nos. I and IV lost 1% and 2.6% respect- 

 ively, while the other three have gained in weight. 



These observations serve to bring out the point under con- 

 sideration, namely, that the large and progressive loss of body 

 weight observed in May is a peculiarity of the spring frogs 

 taken as they are, soon after emergence from the winter sleep, 

 just after the breeding season, and before they have obtained 

 much food. 



In recording the results of this study of R. virescens 

 brachycephala, we shall follow the same order of presentation 

 as in the case of the Bull-frog, and also refer to the earlier 

 paper for some details which it does not seem necessary to re- 

 peat here. In view of the recent date of the paper on the 

 Bull-frog we shall here present the data for R. virescens only, 

 and indicate briefly how these compare with corresponding data 

 obtained from R. catesbiana. 



I. The Weight of the Brain and Spinal Cord. 



The proportional weight of the brain and spinal cord de- 

 creases as the body-weight of the frog increases. This is shown 

 in the following table : 



table v. 



Body-weight Weight value Weight value 



in grms. Sex. of Brain. of Spinal Cord. 



3.34 M. i.43(/, o.57fc 



38.16 M. o.27^c 0.13^0 



76.54 F. 0.20% o.io^o 



