OBSERVATIONS ON THE WEIGHT AND LENGTH OF 

 THE CENTRAL NERVOUS SYSTEM AND OF THE 

 LEGS, IN BULL-FROGS OF DIFFERENT SIZES. 



By Henry H, Donaldson. 



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 showing the weight and length of the brain and spinal cord. 



VI. Explanation of Chart I. 



VII. Method of observation. 



VIII. Explanation of entries in Table 7. 

 IX. Table of records. 



X. Growth. 



XI. Chart II showing growth changes in the brain and spinal cord. 



XII. Explanation of Chart. 



XIII. Observations on the legs. 



XIV. Weight of leg muscles. 

 XV. Length of leg bones. 



Summary. 



(i). In the Bull-frog the relative weight of the brain 

 compared to that of the spinal cord decreases as the frog 

 increases in size. The relative weight of the brain is tempor- 

 arily increased in frogs kept dry for twenty-four hours before 

 death. 



(2). The weight of the leg muscles compared with 

 the weight of the entire frog, slightly decreases as the frog 

 increases in size. In frogs of all sizes, the muscles of the 



