1906] WIEGAND—BUDS AND TWIGS IN WINTER 387 
Of the twenty-seven plants examined there were only eight that 
showed no ice in the buds at —18°C. These eight were sectioned 
later at —26.5° C., with the result that in Castanea, Hicoria, Fraxi- 
nus, and Juglans numerous minute ice crystals were found between 
the cells. It would seem, therefore, that ice may be found in all 
buds if the temperature is sufficiently low. 
The accompanying illustrations are reproductions of photo- 
micrographs taken by the writer during periods of low temperature. 
Fic. 4.—Syringa vulgaris: cross-section through flower bud while frozen; the 
light spaces filled with ice. 
When the mercury registered at zero Fahrenheit or below, freehand 
sections mounted in oil as already described were photographed, 
the apparatus being set up in the open. The conditions for sec- 
tioning were so strenuous that very thin sections could not be obtained, 
and hence the rather poor quality of some of the photographs. The 
palisade-like ice prisms fill the light areas through the mesophyll of 
the scales and young leaves. 
