68 THE ROYAL SOCIETY OF CANADA 



Gadow^ states that "Anura are very susceptible 



to heat; most of them die when their temperature rises to about 

 40° C. Under such conditions they die quickly when in the water, 

 but in the air their moist skin counteracts the heat, lowering it by 

 evaporation; otherwise it would be impossible for a tree-frog to sit 

 in the glaring sun in a temperature of 120° F." 



Miss M. C. Dickerson states^ "The Salientia can endure a greater 

 degree of cold than of heat. It is thought that in water death occurs 

 at 40° C. Thus tadpoles and water frogs are often killed in large num- 

 bers in the shallow pools of Texas. Land frogs and toads hide away 

 in cooler situations under moss and stones in shaded regions and pass 

 through a period of aestivation till lower temperature returns. The 

 tree-frogs can endure much higher temperatures than can dry-skinned 

 toads or water-frogs. It is said that they can sit in the sun at a tem- 

 perature of 60° C. This is possible because of the moisture secreted 

 by their skins. The fact is that they do not actually experience this 

 high temperature because evaporation keeps the surface cooled to a 

 much lower point." 



Lord Lister^ states that " the normal temperature of 



man is deadly to the cold-blooded frog. That animal, which under 

 ordinary conditions exhibits very remarkable persistance of vitality 

 even after somatic death, is killed by being held for about a quarter 

 of an hour in the hand; and if one of its hind feet be similarly warmed 

 the blood-corpuscles will be found packed and stagnant in the vessels 

 of the webs, as if mustard or any other powerful irritant had been 

 applied to them." 



In Pembrey's chapter on "Animal Heat" in Schafer's Textbook 

 it is stated that, according to Delaroche^, a frog exposed to a temper- 

 ature of 45° or 50° C. survived two hours, and further, "It has been 

 shown by Davenport and Castle^ that by gradually raising the tem- 

 perature tadpoles can be kept alive in warm water. Hertwig^ has 



observed that a temperature of 34° is fatal" (to the ova of 



the frog). 



^ Gadow, "Amphibia and Reptiles," (Cambridge Natural History), 1901, p. 68- 



2 Miss M. C. Dickerson, "The Frog Book," (New York, Doubleday Page & Co., 

 1908) p. 16. 



^ Lord Lister, "The Third Huxley Lecture," (London, Harrison & Sons, 1907), 

 p. 13. 



* Pembrey, Schafer's Textbook of Physiology, (Young J. Pentland, Edin. and 

 London) vol. i, 1898, p. 815 (from Delaroche, Journ. de Phys., Paris, 1806, tome 

 Ixiii; 1810, tome Ixxi. 



° Davenport and Castle, Arch. f. Anat. u. Entwicklungsgesch., 1885, Bd. ii, 

 S. 227; quoted by Pembrey, loc. cit. 



^ Hertwig, Sitzungsber, d. preuss. Akad. d. Wissensch., 1896, S. 105; quoted by 

 Pembrey, loc. cit. 



