a ee ee 
1906] WIEGAND—BUDS AND TWIGS IN WINTER 391 
also much wrinkled, those of Negundo and apple showed a slight 
furrowing, those of black cherry and pear scarcely any at all. 
The photographs of wrinkled twigs of Salix cordata, reproduced 
in the accompanying illustrations (fig. 5), were made in the open 
at a temperature of —20° C. The same twigs were then placed 
in the laboratory, and after about one hour were photographed 
again. The slightly wrinkled «appearance in the upper shoot in 
D 
Fic. 5.—Salix cordata: A and B, twigs ears in the open at—20° C., 
showing etic condition due to contraction; C and D, the same twigs thawed in 
the laboratory; the furrows have disappeared except the minute normal striae on 
the lower twig. 
the second photograph was normal for that shoot when thawed, 
during both winter and summer. 
It seemed desirable to determine whether this contraction was 
mainly in the bark or in the wood or in both. At a temperature 
of —18° C. much wrinkled twigs of Salix cordata were collected, 
and the following measurements made: 
