S4 



Kiiaiitlio (181)1) reported that frogs, laid on ice or 

 inil)edded in snow, mud, oi- moisi moss, became I'igid after 

 12 houi's at -1° to -5°. Animals, treated in tliis manner 

 and kept aflcrwards for several days at temperatures 

 between -0.2 and ()..')", reco\'ered completely on iliaw- 

 ing-, even tlioui^h, in the frozen state, tlieir heart had 

 ceased to beat and circulation had, to all appearances, 

 stopped. In niiol her <>roup of experiments, frogs (Ranidae 

 mid Ilijlidac) and toads {Bomhinatorldae and Biifonidae) 

 were frozen so stiff that their extremities could no longer 

 be extended, but not so hard that they could be broken, 

 and were left in this condition for several hours at -0.5°. 

 When they were thawed, only 10 to 157^ of the frogs, and 

 about 507f of the toads survived. None of the animals 

 could withstand a further congelation nor a repeated 

 freezing. Frogs and toads, frozen completely in water, 

 were always killed. (What is meant by ''completely" 

 is not clear.) 



According to Pictet (1893), frogs could be revived after 

 having been frozen hard and brought to a temperature 

 of -28°. To kill them, it required an exposure to -SO"" 

 to - 35°. The lack of information concerning the body 

 temperature of the frogs and the time the animals stayed 

 at that temperature deprives Pictet 's so often-quoted 

 observations of most of their value. 



Kodis (1898) who investigated, among other subjects, 

 the effects of a considerable subcooling on vitality, re- 

 ported that whole frogs, with a thermocouple inserted into 

 the thigh, sutfered no injury when subcooled to - 10°. 

 Isolated frog muscles could be subcooled to - 18°. 



Maurel and Lagriffe (1900) called attention to the 

 rigidity gradually acquired l)y frogs subjected to tem- 

 peratures above zero. They observed that the animals, 

 cooled slowly, were not capable of resuming their posi- 

 tion when set on their back, when their buccal tempera- 

 ture was 8° ; that they showed a complete absence of re- 

 flexes at 4°; and that they became rigid when tlu^y were 

 caught in ice, the buccal temperature (not actually mea- 



