The Electrical Response of Muscle 217 



external evidence of its threefold origin. The temperature of the moist 

 chamber in which the whole preparation lay remained throughout the 

 experiment at 12° C. Through the glass tube lying over the back of the 

 frog iced- water at 4° C. had been running for nearly half an hour before 

 the experiment was begun. After five responses had been recorded, water 

 at 22° C. was passed through the tube for two minutes, and three more 

 responses were recorded. Then water at 5°C. was run through for three 

 minutes and three more responses were recorded. Finallj', water at 24' C. 

 was once more run tlirough for three minutes and three more records wei-e 

 taken. The responses in each case were to the excitation of three different 

 afferent nerves, to the brachial and sciatic of the opposite side, and to the 



0-1 sec. 



I > <> W I W |I W ^^^^ ^ ^^^ 



Fk;. 2. — ReHex electrical responses of frog's triceps f em or is (strychnine). Muscle at l-l' C. 

 in both. Water running through glass tube over spinal cord at 22° C. in A, at 5" C. in B. 

 Recording surface moving horizontally, rate indicated by 100 fork tracing above the signal s. 



sciatic of the same side. Enlargements of the first part of two photogra])hs, 

 taken when the opposite sciatic was stimulated by a break induction shock, 

 are reproduced in fig. 2. When A was taken the temperature of the cord 

 was about 22° C, and it liad been subsequently cooled to about 5° C. when 

 B was taken. The table on p. 218 shows the frequency of the wavelets 

 on the first wave in all the responses in which it could be determined, and 

 the time duration of each of the first four waves. 



In the records of this as in those of most experiments in which the 

 electrical responses of frog's muscle in strychnine spasm were recorded, 

 whether the cord were cooled or not, there is a good deal of variation in 

 the frequency of the wavelets, not only in successive resix)nses, but also at 

 difierent times in one and the same response. When the record is .serial 

 the wavelet frecjuency shows that the rh3'thm usually remains the same for 



