i Es 
1906] WIEGAND—BUDS AND TWIGS IN WINTER 423 
bud-scales function beneficially by mechanically preventing too 
early opening of the buds. That buds, as for instance the horse- 
chestnut and lilac, do open several days earlier when deprived of 
their scales I have frequently noted in connection with the experi- 
ments conducted on desquamated buds in the greenhouse. Still 
the evidence is not sufficiently strong to warrant the assumption 
that this is an important and determining function of the scales. 
Scalcless buds in nature instead of opening very early open quite 
late, and, as ScHUMANNS’ has insisted, many buds during warm 
wet autumns open in spite of the scales. My own observations 
would tend to show that at best they can retard the opening not 
more than three or four days. 
SUMMARY. 
Buds containing a considerable number of well differentiated or- 
gans are usually protected by scales. Those sunk in the bark usu- 
ally contain little besides the growing point or rudimentary leaves. 
Bud-scales are not only the most feasible structures for covering 
a large bud, but they also allow the bud to swell, and protect the 
young shoot when unfolding. 
The bud fundament in most trees is in dad down early in the sum- 
mer, grows gradually till late autumn, remains dormant until early 
spring, then passes through a period of swelling preparatory to 
unfolding. 
Dark-colored buds are usually warmer within than light-colored 
ones; but the question whether there is any relation between dark 
color and the early opening of the buds was not decided. 
Ice may be found in most buds when the temperature has fallen 
as low as— 18° C. and usually in large quantities. Its absence in other 
cases is due to small-celled tissues and meager water content. 
Frozen twigs are smaller than normal ones. Their contraction 
occurs mainly in the bark. 
Frozen buds do not show this contraction so plainly, probably 
because of change of form in the bud-scales. 
The thawing of fie if sufficiently slow, is per degree in inverse 
37 SCHUMANN, C. , Anatomische Studien iiber die Knospenschuppen von 
Coniferen und ak =r ieee Biblioth. Botan. 15:27. 1889. 
