274 



h>(li-a1o(l uiatcrinl as in llic uikIcxcIoixmI huds, are ex- 

 plained on tlie assninj)! ion that when tlic micelles are 

 closer together, as in drier tissue, less damage is done 

 since there is less water to be withdrawn. 



The fact that many of the plants which resist cold are 

 also those which resist drought, in i)ai-ticular, moss and 

 lichens, is adduced as evidence for the theory. 



Sachs' experiments in which plants thawed in w^ater 

 recovered while ])lants thawed in the air died, are in- 

 terpreted as favoring the dehydration theory, since re- 

 covery would be possible when enough water is furnished 

 to rehydrate the cells, while death would occur when too 

 nnich water evaporates, as in the case of thawing in the 

 air. 



To the objection that some plants would be killed by 

 a relatively slight dehydration in freezing while they 

 resist considerable drying under other circumstances, he 

 answers that, in freezing, the withdrawal of water is 

 particularly sudden and acts by its suddenness. 



Moliscli (IHin) contributed important experimental 

 data to the theory of Miiller-Thurgau which he accepted 

 almost entirely. He first pointed out that the theory 

 of a disturbance of the functional harmony cannot ex- 

 plain the cases in which death takes place innnediately 

 upon congelation. He remarked that the theory of a 

 lethal action of temperature alone without ice forma- 

 tion is contradicted by the numerous observations of the 

 innocuousness of subcooling. Finally, he showed that 

 the theory of death by too rapid thawing does not apply 

 in a large number of cases that he studied. Though each 

 of these three theories, he concludes, might explain death 

 in some particular instances, death is, in general, coin- 

 cident with the formation of ice and with its attendant 

 withdrawal of water. 



The following points, several of which had already 

 been indicated by Miiller-Thurgau, are emphasized by 

 Molisch: 1. A relatively large projxntion of ice is formed 



