526 



logical rigidity distinguishable from the physical frozen state. The 

 reaction of frozen muscle, as indicated by litmus paper, is neutral or 

 faintly alkaline, thus differing from recently dead muscles. 



It is not the mere rigidity of the frozen muscle which mechanically, 

 so to speak, prevents contraction, for irritability does not at once and 

 fully return upon thawing. An interval of time may with care be 

 detected in most cases, during which the muscle is already thawed, 

 but yet not irritable ; and irritability returns gradually. 



There is no exact relation between the duration of the frozen state 

 and the duration and amount of the revived irritability. It is not 

 the case that a muscle frozen three minutes regains twice as much 

 irritability, or remains afterwards irritable twice as long as a muscle 

 frozen for six minutes. The frost does not progressively exhaust as 

 it were a given store, leaving, according as the operation is shorter or 

 longer, more or less residue to be manifested when the muscle is 

 thawed. 



The amount of revived irritability will depend in great measure 

 on the treatment the muscles experience when first thawed. The 

 receipt then of a slight shock, which afterwards it will bear with im- 

 punity, if not with advantage, may be sufficient to throw it back 

 altogether into death. 



Nor is the present a case of mere stoppage of the wheels of life, 

 which, when once set in motion again, go on as well as before. 

 Muscles once frozen, however kindly treated, eventually die sooner 

 than those left untouched. There has been in the act of freezing 

 a partial exhaustion of their vital forces. 



I ascertained, by section, that muscles which afterwards regained 

 their irritability were frozen throughout. Hence the revival of irri- 

 tability cannot be supposed to depend upon any part having been left 

 unfrozen. Nor, in muscles partially frozen, did the unfrozen parts 

 seem to have any influence over the life of the frozen parts. 



In muscles which have been well frozen, the fibres are more readily 

 separable from each other, and divisible into fibrillse, than in those 

 which die an ordinary death. Under the microscope, the fibres are 

 clouded and more opake than usual, the transverse striae generally 

 invisible, and in some cases the whole sarcous tissue seems to be con- 

 verted into a confused amorphous mass, lying loose in a sarcolemma, 

 which is more strongly defined than usual. 



