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coiicoiit rated by evaporation from its ])oint of isotonicity 

 with the normal nniscle until it had lost 78'/ of its water. 

 Death by freezing- would then take ])lace when more than 

 this |ti-()i)()rtioii of watci- freezes out from the already 

 concentrated })rotoi)lasm. (A determimition of the freez- 

 in«^ point of a solution containini;- the salts of the nmscle 

 at the concentration reached after drying to the critical 

 degree gave 1.6".) 



The similarity of action of freezing and drying was 

 further evidenced by the similarity in the changes of the 

 electric resistance observed in tissues which were killed 

 by either of the two injurious agents. 



Moran, however, remarks that the action of freezing 

 and that of drying are not altogether identical on all 

 sorts of materials. Drying is not known ever to pro- 

 duce an irreversible change in gelatin gels, while freez- 

 ing does. 



As to the mechanism by which a removal of water be- 

 comes injurious, he makes the following suggestions : 1. 

 Dehydration may result in a destruction of "an interface, 

 a catalyst, or a structure holding catalysts"; 2. It may 

 upset the ionic balance and cause a change in the vis- 

 cosity and permeability of protoplasm; 3. It might pro- 

 duce some internal strains of the type observed in gels 

 which become anisotropic by being frozen and thawed. 



Com])aring death to the irreversible change brought 

 about at - 6 in frozen egg yolk and probably due to the 

 action of concentrated electrolytes on the protein-lipid 

 complex, Moran sees ''closely similar relations" in the 

 two cases; they would ditfer, however, in the fact that the 

 irreversible change in yolk requires some time so that 

 one can avoid it by rapid cooling, while "no sensible time 

 appears to be needed for permanent destruction" of the 

 living system and it is impossible, by rapid freezing, to 

 avoid death. 



Some of the authors who hold the dehydi-ation theory 

 of death bv cold assume that if the water withdrawn can 



