1906] WIEGAND—BUDS AND TWIGS IN WINTER 379 
them were killed. The unwhitened buds swelled and grew percep- 
tibly before any swelling could be detected in those that were whitened. 
The difference in size March 20 was plainly shown in drawings 
of the sections of the two classes of buds. Whitened trees came 
into bloom about one day later than unwhitened trees of the same 
variety. In 1896-97, owing to a more moderate spring, the differ- 
ence in time of flowering was still greater. The whitened buds 
of each variety opened two to six days later than those that were 
not whitewashed. 
The differences in the actual time of flowering, however, does not 
express the difference in time of the swelling of the buds. The 
whitewashed buds did not begin to swell until almost time for the 
flowers of normal trees to appear, while the unwhitened ones began 
to swell three or four weeks earlier, as shown by the drawings above 
mentioned. 
These experiments of WHITTEN seem to show that in the peach, 
at least, the dark-purple color of the buds tends to cause earlier 
activity in the spring, accompanied by earlier swelling and flower- 
ing. The only doubt, it seems to me, lies in the effect of the white- 
wash upon the growing tissue. As mentioned below, some non- 
porous substances seem to retard respiration perhaps to such an 
extent that growth also is retarded, but the whitewash would seem 
porous enough to escape this criticism. In a more recent paper 
Wuirren® has shown that the temperature within whitened and 
unwhitened twigs differs by several degrees. In bright sunlight 
the difference was as much as 15° C., the unwhitened being the 
warmer. The whitened twigs were nearly of the same tempera- 
ture as the atmosphere. 
WuitTENn® has also shown that purple peach twigs transpire 
considerably more than green ones. This was probably due to 
the greater temperature and is probably an additional factor in 
the winter-killing of the peach. 
8 WarrreN, J. C., Preventing frost injuries by whitening. Pacific Rural Press 
60:276. 1900. 
9 WHITTEN, J. C., Das Verhiltnis der Farbe zur Tétung von Pfirsichknospen 
durch Winterfrost. Inaug. Diss. Halle. 1902. p. 35. See also in this connection 
Macoun, W. T., Some results of experiments in spraying, etc. (whitewashing ” 
Tetard bud development.) Ontario Fruit Growers Ass. Rep. 1899: 100, and “ Experi- 
mental Farms,” Canada, 1899:92. 
