OBSERVATIONS ON THE WEIGHT AND LENGTH OF 

 THE CENTRAL NERVOUS SYSTEM AND OF THE 

 LEGS IN FROGS, OF DIFFERENT SIZES (RANA 

 VIRESCENS BRACHYCEPHALA— COPE). 



By Henry H. Donaldson and Daniel M. Schoemaker. 

 Contents and Summary. 



Introduction. 

 I. Weight of the brain and spinal cord. 

 II. Ratio of the weight of the brain to that of the spinal cord. 



III. Post-mortem changes in weight of central nervous system. 



IV. Influence of water absorbed by the living frog on the weight 



of the brain and the spinal cord. 



V, Chart I, showing the weight of the brain and spinal cord. 



VI. Explanation of Chart I. 



VII. Method of observation. 



VIII. Table of records. 



IX. Explanation of entries in Table VII. 



X. Growth. 



XI. Weight of leg muscles. 



XII. Length of leg bones. 



XIII. Fubini's observations. 



Summary. 



1. The males of Rana virescens brachycephala rarely at- 

 tain a body weight above 50 grms. The females (without ova- 

 ries) may weigh 75 grams or more. 



When the average of the largest males is compared with 

 females yielding the same average weight, the males are found 

 to have the lighter brain and spinal cord. 



2. Spring frogs tend to lose weight rapidly when kept in 

 the laboratory. This tendency diminishes as the season ad- 

 vances toward autumn. 



