324 Journal of Comparative Neurology. 



legs or of other damage, and were therefore rejected. For 

 some reason, specimens weighing between lOO and 130 grams, 

 were not found. It is possible that this was a mere accident, 

 but it is also possible that at that weight, the frogs most readily- 

 escaped capture and hence were not brought in. 



The observations recorded in Table 7 were made on Bull- 

 frogs (R. catesbiana) during the summers of 1897 and 1898. 



All the specimens were examined shortly after capture, 

 only a few being kept more than ten days. 



While awaiting examination, the frogs were protected from 

 the light in boxes or dishes, for the most part so arranged that 

 the animals could be in or out of water at will. 



All weights were taken on balances sensitive to half a mil- 

 ligram. In referring to the tables, the records which involve 

 the examination of the legs as well as the nervous system, are 

 termed "complete " records, while those involving the nervous 

 system only, are termed "partial records." 



In every case, however, the " partial records" represent 

 special observations and are not fragments of those intended to 

 be complete. 



The following account gives in detail, the manner in which 

 the complete examination of a frog was made. 



The frog was killed with chloroform or ether, and at once 

 weighed entire. 



The length was taken. The legs were next separated from 

 the body and severed at the knee and ankle joints, thus dividing 

 each leg into three segments. Each segment was placed im- 

 mediately in a closed weighing bottle. 



As a rule, the left leg was dissected first ; it having been 

 found that the weight relations of the two legs were not affected 

 by the order in which they were dissected. 



Before weighing the segments of the leg, the brain and 

 spinal cord were exposed, their lengths taken, and then each 

 removed to a small weighing bottle and weighed at once. 



The sex was next determined. Lastly the weights of the 

 stomach contents and the ovaries, when present, were ascer- 

 tained and substracted from the body weight as first taken. 



