525 



degree of heat which resembles frost in depriving them of irrita- 

 bility." 



Having myself made some experiments on this subject, I venture to 

 lay them before the Society. 



Two methods were adopted to freeze the muscles. In most in- 

 stances I securely enclosed them in little bags of thin gutta percha, 

 and so buried them in a mixture of salt and snow, or pounded ice. 

 At other times I suspended them in pure olive oil, contained in a small 

 vessel surrounded by the freezing mixture ; having previously ascer- 

 tained that immersion for two hours at least in the same oil, at an 

 ordinary temperature, had no injurious effect upon muscular irrita- 

 bility. 



The results I came to were as follows : 



1. Completely frozen muscles are not irritable to the strongest 

 stimulus we possess. 



2. Muscles which have been frozen for a short time only (five or 

 ten minutes at the longest) may regain their irritability on being 

 thawed. 



3. Muscles which have been frozen for more than ten minutes 

 never regain their irritability. 



The loss of irritability seems to be due more to the occurrence 

 of freezing than to any mere fall of temperature. For although 

 the irritability does diminish with the fall of temperature, and 

 markedly so when the freezing-point of water is neared, yet the 

 great loss and final extinction takes place only when the tissue itself 

 is frozen. 



I know of no method of treating a muscle so as to lower the free- 

 zing-point of the water contained in its tissue, without so injuring it 

 as to render such a procedure useless for the present purpose. 



In order that the irritability of any muscle should wholly disap- 

 pear, the muscle must be wholly frozen. A muscle may be in great 

 part frozen, and yet capable of producing a movement when stimu- 

 lated, by the contraction of the unfrozen part. 



The passage into the frozen state is accompanied by no contrac- 

 tion. Frogs' limbs freeze exactly in the same position which they 

 were previously maintaining ; and when the individual muscles were 

 frozen singly, I was unable to satisfy myself of the occurrence of any 

 contraction. Nor could I assure myself of the advent of any physio- 



