A CHEMICAL SIGN OF LIFE 



platinum wires fused into the side of the apparatus (see 

 p. 113), these wires being connected in turn with the 

 induction coil. Under this condition, when neither 

 nerve is stimulated, the amount of the precipitate is 

 equal in the two chambers. However, when one of the 

 nerves is electrically stimulated with a weak induction 

 current, the distance between the primary and second- 

 ary coils being more than 

 8 10 cm., an ordinary dry 

 battery being used, not 

 only does the precipitate 

 appear sooner in the cham- 



FIG. 2. Glass weighing plate. 

 A, B, platinum wires fused in the 

 rear of the glass plate, with hooks; 

 C, the nerve which is' stimulated 

 at D; G, the plate proper. Another 

 piece of glass, exactly counter- 

 balanced with this plate, is used, 

 so that any wet tissue can be 

 weighed very quickly. 



ber containing the stimu- 

 lated nerve, but the 

 quantity of the carbonate 

 is much greater. This 

 difference in carbon diox- 

 ide production can be 

 brought out better in the 



quantitative estimate made 

 in the manner described above. 



As shown in Table V, a stimulated nerve fiber 

 of the spider crab gave i6Xio~~ 7 g. of carbon dioxide for 



TABLE v 



Nerve 



Non-medullated (spider 



crab) 



Medullated (frog).. . . 



Amount of CO 2 Pro- 

 duced by 10 mg. of 

 Resting Nerve in 

 10 Minutes 



6.7Xio~7g. (i 5 -i6) 

 7 g. (iQ-2o ) 



Amount of CO* Pro- 

 duced by 10 mg. of 

 Stimulated Nerve in 

 Minutes 



10 



16. Xio-7 g. (i 4 -i6) 

 14.2X107 g . ( 2 o-22) 



Rate of 



Increase 



of CO* 



2.4 times 

 2.6 times 



10 mg. of the nerve for ten minutes, while a fresh 

 unstimulated nerve of the same animal gave only 



