salt solution, was anisotropic (Luyct and Thoennes, 

 193Sa). 



Plant loaves can be vitrified, at least partially, when their 

 water content is not too hi<ih. We have shown this in the 

 followinii' mannei'. A leaf which, wlieii examined against 

 a source of light (an electric lamp) exhibits a certain 

 degree of translncidity, is dipped into liquid air. It be- 

 comes hard and ])reakable but its degree of transparency 

 has hardly changed when one takes the leaf out and again 

 examines it against the lamp. After a few seconds of 

 exposure to room temperature one sees the leaf become 

 considerably oi)a(iue and, a few seconds later, it again 

 acquires its original translncidity. It seems evident that 

 all the water of the leaf was not frozen at the temperature 

 of liquid air, that it froze only when the temperature rose 

 to the zone of devitrification, and that it melted at a still 

 higher temperature. The leaves treated in the manner 

 described showed little or no vitality. Though this mate- 

 rial allows of an easy observation of vitrification and devit- 

 rification, we think that it could not be subjected to vitro- 

 fusion (the transition from the vitreous to the liquid state 

 without passing through the crystalline state), even when 

 boiling water was used as the warming bath. 



Moss gave results in perfect agreement with our antici- 

 pations (Luyet and Gehenio, 1938). Specimens of the 

 genus M)iiiiw were placed in containers in which solutions 

 of sulfuric acid of known concentration maintained an 

 atmosphere having a given degree of humidity. After a 

 stay of less than 24 hours in one of these containers, a state 

 of equilibrium was established. A portion of the moss was 

 then taken out for a determination of the water content, 

 while the remainder was immersed in liquid air and in 

 water at 20°. The vitality of the cells was tested by plas- 

 molv«is. The results can be summarized as follows: 



