278 



iiK'i-cascs as a rcsiill of the iciiioxal of watci" (the de- 

 tails of tliis llicory will he i;i\('ii hclow). 



Vit'ifitUnidir / IHO'.i), rcsniiiiii.u' the x'icws of Mcz, claims 

 that the ('I'll sap usually ))r('S('ii1s a cutcctic ])()int at 

 around - (i . lie. thcrcfoi'c, denies that thei'e can ])e any 

 further desiccation at the tenijx'iatui-e of '.]() at which 

 some ])lants die. 



The same author argues that if death is due to some 

 watei- withdrawal, oi- to the salting' out of some protein, 

 or to the eutectic fi'eezin.n' of some complex mixture, some 

 thermal effect should ajjpear. Xone, however, has ever 

 been observed. 



One of the most natural explanations of the fact ob- 

 served so many times that a tissue survives the forma- 

 tion of ice in the neii^hborhood of its freezing- point and is 

 killed on further freezing at a loAver temperature is 

 that, as long- as there is free water to freeze, no damage 

 is done, and that injury begins when more strongly 

 bound water freezes. Jensen and Fischer (1910), found, 

 in a comparison of the freezing curve of frog's muscle 

 with that of an isotonic salt solution, that only about 3,9% 

 of the water of the muscle might be more firmly bound. 

 Besides, the dead muscles also seemed to contain bound 

 water. Death, therefore, could hardly be explained by the 

 unl)in(ling of that water. 



According to Irmscher (1912), the similarity pointed 

 out by other investigators in the resistance of plants to 

 injury by drying and l)y freezing can also be observed 

 in moss. In general, the species which are more resis- 

 tant to cold are also more resistant to drought. (There 

 are, however, several exceptions.) 



Another similarity between the mechanism of action of 

 desiccation and that of freezing, pointed out by the same 

 author, is that cold hardiness can be induced by expo- 

 sure to drought as well as by exposure to cold. Moss 

 which had been dried and which regained its full turgor 

 bv innnersion in water was found more resistant to cold 



