VOLUME XLI NUMBER 6 
DOTANICAL. GAZETTE 
JUNE, 1906 
SOME STUDIES REGARDING THE BIOLOGY OF BUDS 
AND TWIGS IN WINTER.’ 
Karu M. WIEGAND. 
(WITH EIGHT FIGURES) 
Durinc the winter months in temperate and arctic climates, 
the meristematic tissues of shrubs and trees assume a more or less 
completely dormant or resting condition, and become separated 
from the surrounding atmosphere by tissues of varying thickness 
and varying degrees of resistance to the passage of water vapor. 
A detailed study of these structures during the cold period has brought 
out many interesting facts ordinarily escaping casual observation. 
In the twigs the cells of the cambium lie close together without 
intercellular spaces, but the cortical cells usually do not touch at 
the corners, and consequently in the cortex there is a more or less 
elaborate system of intercellular spaces. The main structural pro- 
tective measure seems to be the firm epidermal layer with heavily 
cutinized outer wall, which is always present at this period. 
There were no stomates on the twigs in any of the species I exam- 
ined. Gas diffusion takes place mainly through the lenticels; but 
perhaps to a slight extent also through the cuticle its:lf. All the 
living cells contain a large amount of water, 51-55% in most fruit 
trees, 63% in Forsythia, and the quantity in each species is remark- 
ably constant, rarely varying more than four to five per cent., and 
usually even much less. 
Regarding the time during the ‘ital summer when the bud 
fundament is first distinguishable, ALBERT? found that, out of 
r aay from the Department of Botany of Cornell University. No. 105. 
2 ALBERT, P., Beitrage zur ee der Knospen einiger Laub- 
hélzer. Forstlich naturw. Zeitschr. -3:345, 393- 1894- 
Shoe 
