Heat-Coagulation of Muscles of Northern and Southern Frogs. 555 



in table) the first contraction continued from its commencement until 

 the second contraction commenced, evidenced in the tracing by a 

 continual but gradual rise until the temperature necessary for the 

 second contraction was attained, when the rise became more abrupt. 

 In every instance a gradual but continuous rise was obtained follo- 

 wing the second contraction. The muscles were usually not heated 

 above 80 degrees because of the liability of the muscles to break 

 when the connective tissue was changed into gelatine. 



Table IV. The stomach shows, firstly, a marked relaxation between 

 the temperatures of 40.5 and 51.5 degrees; secondly, a contraction 

 starting at the high temperature of about 54.2 degrees and with no 

 upper limit to this contraction. The continual rise of the writing 

 point is in part due to the fact that in coagulating the stomach 

 muscle curls up like a bow. 



Table V. The urinary bladder in frog 16 showed a relaxation 

 commencing at 28.5 degrees which was so gradual that its end could 

 not be determined. In all these frogs the bladders broke at about 

 64 degrees C. because of gelatine formation. 



Table VI. Shows a comparison between muscles which were 

 fatigued previous to the heating process, and the corresponding un- 

 fatigued muscles of the opposite limb. To produce fatigue, tetanizing 

 currents were used, which were applied either directly to the muscle 

 or through the sciatic nerve. In some instances the muscles were 

 fatigued in situ, in others the muscles were stimulated after removal 

 from the body and after immersion in the salt solution. In every 

 instance the pair of muscles (one fatigued, the other unfatigued) of 

 the same frog were heated at the same time in the same vessel. 



Table VII. Sartorius muscles of small frog. To be compared 

 with Table I of large frogs. 



Table VIII. Stomachs of small frogs, to be compared with 

 Table IV. In frog 6, half of the stomach was kept for one hour in 

 l°/ nicotine in normal salt solution and in frog 7 half of the stomach 

 was kept in atropine 1 / 500 in normal salt solution for 20 minutes, 

 with a view of testing nervous factors. 



Table IX. Gastrocnemius muscles of small frog to be compared 



