62 



A CHEMICAL SIGN OF LIFE 



in the narcotic solution, care being taken that the claw 

 muscle did not come in contact with the solution. After 

 ten minutes it was removed, freed from excess liquid by 

 means of filter paper, its state of excitability determined 

 by stimulation, and, with claw attached, it was placed 

 in a moist chamber for ten minutes, which is the time 



TABLE VII* 

 EFFECTS OF ETHYL URETHANE ON CLAW NERVE OF SPIDER CRAB, Libinia canaliculata 



* Since our previous determinations of the carbon dioxide production of the spider 

 crab's nerve were made at a much lower temperature (15 to 16 C.), the work was 

 repeated at the higher temperature at which most of the present experiments were made. 

 In order to make the comparison a rigid one, the normal nerve was subjected to a treat- 

 ment similar to that employed with the narcotized nerve, except that it was not narcotized. 

 It was isolated, quickly weighed, and immersed in sea-water for ten minutes, after which 

 the rate of carbon dioxide production was determined in the usual way. As was expected, 

 the nerve exhibited a somewhat higher rate of metabolism at the higher temperature. 

 The results are incorporated in the table. 



usually required in making a determination of the 

 carbon dioxide production. After this the nerve was 

 brought back to fresh sea-water and the return of irrita- 

 bility was determined, as evidenced by contraction of the 

 claw or joint in response to the electrical stimulation 

 of the nerve. Thus the essential conditions obtaining 



