1906] WIEGAND—BUDS AND TWIGS IN WINTER 405 
ice cake, since it depends largely upon the non-conductivity of the 
ice and the greater quantity of heat required to convert ice into 
water. This heat is more slowly available when the change is 
gradual. Although no experiments were made under these condi- 
tions, it is to be expected, I think, that with long slow rise in atmos- 
pheric temperature, the retarding effect would almost if not quite 
disappear. Frozen peach buds, placed in the air at—5.5° C., which 
gradually rose in 2 to 2.5 hours to a temperature of —1.0° C., were 
completely thawed, apparently as soon at the temperature reached 
about —2.3° C., thus following the general rule for frozen tissue. 
We are now in position to consider the questions outlined on a 
previous page regarding the various ways in which the bud-scales 
May be supposed to act beneficially by modifying the temperature. 
It was first suggested that they might retard the thawing out 
and thereby be of benefit to the bud. From the tables already 
given and the observations regarding them, it becomes at once 
apparent that the temperature modification which scales are capable 
of producing are, in the cases of moderate sized buds, of very little 
Moment—not more than two or three minutes during most of the 
time, and then only when the change from one temperature to 
another is abrupt. When the transition is gradual, the retarding 
effect will be very slight indeed, and is frequently wholly offset by 
the absorbing power of the darker color. I cannot see how under 
any atmospheric condition the modifications can become great 
enough to be noticeable unless careful measurements are taken. 
The idea that a slow thawing is beneficial to plants has come about 
from analogy with the frosting of human tissue and from the con- 
sideration of the treatment which gardeners successfully give frosted 
plants. But the gardener’s treatment consists in keeping the 
plant cool and dark for hours or even days after the freezing; while 
recent investigators have shown that slow or rapid thawing (7. e. 
conversion of the ice into water) in themselves bear no relation 
Whatever to the extent of the injury. The gardener’s treatment 
is essentially an after-treatment—while the plants are recovering 
from the shock. I have already cited the fact that buds of many 
trees, at least, may be thawed in an oven and then frozen alter- 
nately many times and still come out in the greenhouse apparently 
