1906] WIEGAND—BUDS AND TWIGS IN WINTER 385 
depending upon the resistance of the walls, and often occupied 
a space smaller than the ice itself. These cells were uninjured, 
however, and would resume their normal condition on thawing. 
In all cases more ice was found in the scale than in the young shoot; 
never between the scales but always in the mesophyll. The cells 
of the embryonic shoot were so much smaller and their water content 
so much less, that frequently it was difficult to detect any ice forma- 
Fic. 2.—Populus dilatata: cross-section of bud, showing ice in bud-scales and 
foliage leaves. 
tion whatever; but ordinarily very minute and numerous masses, 
at least, were scattered between the cells, and sometimes there were 
large masses such as appear in the outer organs. In young anthers 
the ice often filled almost the entire anther cavity, and in it the pollen 
grains were imbedded in a completely collapsed state. 
The results of the observations regarding the occurrence of ice 
in buds may be summarized briefly as follows. The temperature 
Was ~33;5° C.to = 28°. 
