546 Messrs. M. Back, K. M. Cogan, and A. E. Towers. 



Series 3. — The comparison of these results with the controls left no doubt 

 in our minds that the stimulated muscles really did gain in weight. In order 

 to test the matter in another way we determined the specific gravities of the 

 stimulated and unstimulated muscles by weighing them in Einger's solution. 

 Our argument was that if the muscles merely differed accidentally in size, 

 their specific gravities would be the same. Even if the difference in size was 

 due to a greater amount of blood in the stimulated muscle, the specific 

 gravities would be much the same on account of the relatively high specific 

 gravity of blood. If, on the other hand, the difference in weight was due 

 to the stimulated muscles taking up water from the blood as an osmotic 

 phenomenon, the heavier muscles should have the lower specific gravity. 



Average weight of 

 muscle. 



Excess of stimulated 

 muscle. 



Specific gravity of 

 stimulated muscle. 



Specific gravity of 

 unstimulated muscle. 



mgrm. 



mgrm. 







192 



37 -0 



1061 



1 -073 



257 



25 -0 



1 -064 



1 -075 



235 



7-8 



1 -075 



1 -078 



237 



3-2 



1 -065 



1 -066 



323 



28 -4 



1 -070 



1 -069 



With the exception of the fifth, the differences in specific gravity bear out 

 our contention. To these we may add some data from muscles which were 

 tested at longer intervals of time after stimulation. 



Average weight of 

 muscle. 



Excess of stimulated 

 muscle. 



Specific gravity of 

 stimulated muscle. 



Specific gravity of 

 unstimulated muscle. 



mgrm. 



mgrm. 





1-075 



437 -5 



7-2 



1 -069 



456 -4 



5-8 



1 -069 



1 -072 



281 -6 



6-1 



1 -067 



1 -069 



394 -6 



14 -4 



1 -068 



1 -071 



227 -4 



27 -6 



1 -073 



1-087 



Series 4. — In all the above experiments the shocks passed through the 

 muscle ; in order to exclude the possibility of some direct electrical effect on 

 the blood vessels or on the muscular tissue, we performed another series of 

 experiments in which the frogs were killed as before, by destruction of the 

 cerebrum and basal ganglia, but the spinal cord was not pithed. The two 

 sciatic nerves were dissected out in the thigh and were cut, one was ligatured 

 and stimulated. This technique appeared very satisfactory, the dissection of 

 the nerves entailing less bleeding than the pithing of the lower part of the 

 cord. 



