214 Buchanan 



Experiments in wliicli the temperature of the recording muscle 

 was varied, while that of the rest of the frog remained 

 constant. 



For these experiments the gastrocnemius was chosen as recording 

 muscle, and was prepared so that it remained in connection with the rest 

 of the preparation by its sciatic nerve only. The nerve ran through an 

 aperture in the wall dividing two moist chambers, in the one of which was 

 the muscle, in the other the decerebrate frog. The temperature of the 

 muscle chamber was varied by placing over it now a tray of iced water, 

 now one of warm water. 



In the experiment to which tig. 1 relates the iliac artery had been 

 ligatured on the left side and 5 minims of 1 per cent, curare injected into 

 the dorsal lymph sac : then, when the curare had taken effect, 1 minim 

 ()"1 per cent, strychnine acetate had been injected and half an hour later 

 the left gastrocnemius prepared and arranged in the way just described. 

 Its tendon end was connected in the usual way with the mercury of the 

 electrometer, a spot on its dorsal surface with the acid. The muscle was 

 excited each time by a single break induction shock applied to the skin of 

 the back of the frog. The temperature of the moist chamber in which the 

 body of the frog was lying remained at 12° C. throughout the experiment. 

 Twelve records were tirst taken with the muscle also at 12° C. None of 

 these exhibit more than a single wave, on the rise of which are wavelets 

 which in nine of the records have a frequenc}' of 100 ± 3 per second, in 

 two of them (the fifth and the sixth) one of about 90 per second, and in 

 one (the first) one of 110 per second. The twelfth record is reproduced in 

 fig. 1, A. 



The muscle chamber was then cooled, and when its temperature was 

 10" C. the record reproduced in fig. 1, B, was taken. The f requeue}" of the 

 wavelets is 81 per second. A second record, taken after the muscle had 

 been cooled to 9" C, showed a wavelet frequenc}' of 70 per second. 



The preparation was now left for an hour and a half, the muscle 

 chamber remaining covered b}' the ice-tray, and its temperature being 7' C. 

 at the end of tlie time. The only muscle which contracted when the skin 

 was stimulated was, as before, tlie recording gastrocnemius, which had been 

 protected from the influence of the curare. The contraction was now no 

 longer twitch-like as it had been in the morning, but ^as, each time, a 

 long and steady spasm. All the electrical responses were now serial, waves 

 as well as wavelets being seen in the records when the plate was travelling 

 at a sufficiently slow rate to show them. Five records of the reflex re- 

 sponse were taken with the muscle at 7° C, of which the last is reproduced 

 in fig. 1, C. The muscle chamber was then allowed to return to the tem- 

 perature of the room and the record reproduced in fig. 1, D, was taken. 

 It was then wanned beyond the temperature of the room and five records 

 were taken with the temperature of the muscle rising to 16 C. The last. 



