1906] WIEGAND—BUDS AND TWIGS IN WINTER 381 
60 
SS Ee 
50 —— 
ri 
40 L 
a a 
a 
380 
me oe» « & & &® & & Sk & 8S & SK EF B 
———horsechestnut bulb; .<.s.07:- naked bulb. Abscissas represent 5° F.; 
BIG. he 
ordinates, 2 minutes. See Table I. 
No further rise was noted, although the instruments remained 
in place more than an hour. The experiment was repeated several 
times during the spring, both with the same bud and with a fresh 
one, in every case with practically the same result, namely a much 
faster rise in the bud-bulb, amounting finally to an excess cf 5 to 
12° C. over the other bulb. 
That the above differences were due mainly to the dark brown 
color of the bud seems probable from another series of experiments 
in which the naked thermometer-bulb was coated with brown 
drawing ink. Readings were taken under the same conditions 
as before. In these cases the difference was but slightly in favor 
of the horsechestnut bulb, probably because of the less highly pol- 
ished surface of the ink bulb. It would seem, therefcre, that the 
point is fairly well demonstrated that in the case of the horsechestnut, 
at least, the color does make considerable difference in the absorb- 
ing power of the bud as regards heat. Although no experiments 
were performed, there seems no reason why the same shculd not 
be true also of other dark-colored buds. 
With these results in mind I made a few observations one spring 
to see if there was any relation between the color of the buds and 
the time of swelling and opening. It seemed reascnable to expect 
that the darker the bud, and consequently the more heat absorbed, 
the earlier the bud would swell and open in the spring; and all the 
more because this was the exact conclusion reached by WHITTEN 
with his peach experiments. Unfortunately, accurate record of 
the time of swelling and of opening were not kept; but still I believe 
