124 THE ROYAL SOCIETY OF CANADA 



Summary of Results. 



(1) Frogs freeze at a temperature of -0-44°0-±02°C., in a 

 manner very similar to that of solutions isotonic with their tissue-fluids. 



(2) Specimens of R. pipieîis obtained from the neighbourhood of 

 Chicago will survive a temperature of -1°C. They will not survive a 

 temperature of -1 •8°C. 



(3) The heart-tissue, whether exsocted or in vivo, of these frogs 

 survives a temperature of -2 • 5°, but is killed by a temperature of -3 • 0°C. 



(4) Since this is the case, and since similar experiments by other 

 observers have shown that muscular tissue will survive a temperature of 

 -2-9°C., while the peripheral nerves are not killed by much lower 

 temperatures, it appears probable that the cause of death is connected 

 with a specific temperature effect on the brain or cord. 



(5) It is unlikely that frogs survive the low temperatures of the 

 atmosphere, and superficial layers of the earth, of a Manitoban winter. 

 Their winter quarters are probably situated in a layer of mud or soil 

 which retains a temperature above or in the neighbourhood of 0°C. 



We desire to thank Professor Swale Vincent for his continued and 

 stimulating interest in these experiments. 



This work has been carried out in connection with a Committee of 

 the British Association for the Advancement of Science, appointed to 

 consider "The effect of low-temperature on cold-blooded animals." 



The expenses of the research have been in part defrayed by a grant 

 to Professor Vincent from the Government Grant Committee of the 

 Royal Society of London. 



