DoNALDSON-ScHOEMAKER, Nervous System of Frogs. 119 



as well as the nervous system, are termed 'complete,' while 

 those involving the nervous system only, are termed ' partial 

 records." In every case, however, the ' partial records ' rep- 

 resent special observations and are not fragments of those in- 

 tended 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 seg- 

 ment was placed immediately in a closed weighing bottle. 



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- 

 taained and subtracted from the body-weight, as first taken. 



The bottles containing the segments of the legs were then 

 weighed separately. Next each segment was removed from 

 the bottle and the bottle itself freed from any fluid that had 

 collected in it. The skin, together with the bone (or bones), 

 freed as completely as possible from the muscles and tendons, 

 were returned to the dry bottle, which was then weighed for 

 the second time. The difference between the first and second 

 weighing gave the weight of the muscles of the respective seg- 

 ments. 



The length of the leg bones was determined. This last 

 measurement was made while the bones were fresh and moist, 

 since they shorten on drying. 



