112 



THE ROYAL SOCIETY OF CANADA 



tures at which the frogs perished. They show tliat exposure to a certain 

 low temperature (-12°) for a period of one hour does not suffice to 

 reduce the internal temperature of the frog to the death-point. 



In certain other experiments the initial cooling effect is clearly- 

 evident in the frog, (compare for example experiments 20 and 22) 

 though in this case it is shown in the solution only.* The actual freezing- 

 point temperature according to the most exact experiment (20) which 



Il r;l4t;l4iitfcnii!Sl Umffl i liliH ii ii fitUiMr}^iliii;t^ 



Figure 1 



we have performed is —0-44° di 0-02°C. This is in good agreement 

 with similar experiments with frog's muscle by Brunow,t who obtained 

 the freezing-point — 0-42°. He also has obtained curves for the ex- 

 sected muscle very similar to that in figure l.f 



*Tliis supercooling effect is apparently a general phenomenon. Thus Bach- 

 metjew (Zeit. f. wiss. Zool., 66, 521; Zentr. f. Physiol., 13, 776, 1899) has obtained 

 the same effect for butterflies (Saturnia pyri) and other insects. He is of the opinion 

 that this property is of importance for species which survive the winter. Since, as 

 will be seen later, a frog can survive the solid state, his views on the importance of 

 supercooling seem exaggerated. 



fLoc. cit., p. 8. Cp. also Jensen and Fischer, Zentr. f. Physiol., 23, 296-7, 

 1909. 



