Section IV., 1915 [67] Trans. R.S.C. 



The Upper Limit of Temperature Compatible with Life in the 



Frog. 



By A. T. Cameron and T. I. Brownlee. 



(From the Department of Physiology and Physiological Chemistry, 

 University of Manitoba, Winnipeg.) 



Presented by Professor Swale Vincent, F. R.S.C. 



(Read May Meeting, 1915.) 



In previous communications^ the authors have determined the 

 lower limits of temperature compatible with life in the frog. These 

 were found to be —1 -25° ± 0-15° C. for R. pipiens, and for R. clami- 

 tans and R. sphenocephala a few tenths of a degree higher. These re- 

 sults were obtained from experiments in which the minimal temperature 

 was maintained for one hour. At such temperatures the tissues of 

 the frog were not killed. Muscle, nerve, heart, and brain and cord 

 (in response to gross stimulation) reacted normally after the animal 

 was brought back to room temperature. We considered that the cause 

 of somatic death was probably a specific temperature effect upon 

 some part or parts of the central nervous system. 



Somewhat similar results, as regards the minimal temperature 

 at which life is possible, have recently been obtained for fish {Funduliis 

 heteroclitus, the common mummichog) by W. H. Martin.^ 



The present paper contains the results of a number of experiments 

 designed to ascertain the corresponding upper temperature limit for 

 the frog, and to see whether the cause of death in this case was 

 particularly connected with the central nervous system or could be 

 traced to some other factor. 



Published data bearing on the subject are apparently not very 

 considerable in amount, and the greater part seems to be indefinite, 

 if not inaccurate. Unfortunately library facilities here have not per- 

 mitted an exhaustive search after data which from their nature are 

 probably widely scattered and frequently noted incidentally in work 

 on other problems. 



lA. T. Cameron and T. I. Brownlee, Trans., 1913, Vol. VII, Sect, iv, p. 107; 

 A. T. Cameron, ibid., 1914, Vol. VIII, Sect, iv, p. 261. 



2 W. H. Martin, "Some experiments on the freezing and thawing of live fish," 

 Contributions to Canadian Biology, Sessional Paper 39b, Ottawa, 1915, Fasc. I, p. 

 73. 



Sec. IV, 1915— 5a 



