1921] _. STRAUSBAUGH—DORMANCY AND HARDINESS 341. 
under favorable conditions of temperature development proceeds 
normally, no matter at what stage of the dormant period the col- 
lection is made. On the other hand, the buds of Assiniboine 
collected before the middle of January are so deeply dormant that 
under the same conditions of temperature no visible change takes 
place and no blossoms are produced. Buds of Assiniboine, col- 
lected on January 24, bloomed 26 days later, on February 18. 
As this is the first visible response of these hardy buds, it is assumed 
to indicate the previous occurrence of some internal change which 
determines the breaking of the dormant condition. At this same 
TABLE I 
DEGREE OF mea OBTAINING IN HARDY AND SEMIHARDY BUDS AS MEASURED BY 
EQUIRED FOR BLOOMING UNDER LABORATORY CONDITIONS AT 
DIFFERENT INTERVALS DURING SEASON OF DORMANCY 
STELLA TONKA ASSINIBOINE 
Time Time Time 
Date of Date of |required| Date of Date of |required| Date of Date of [required 
collection bloom aa) a collection bloom for collection bloom for 
bl bloom bloom 
Oc et So 1 eed Oe, Lee AT Se Bisa de dence ee 
ov. 3 | Noy. #41 ¢¢ |. Nov. 8 t Nov. as | tg [Nov. 87...-...0.8..55. 
Nov. 19 | Dec. 4 
Jan. 24 | Fe 3) 30 | jal. 441 Fev. 2} 10.7 Jan. 24} Feb, 18) 26 
Mar. 5 Mar. 13 9 | Mar. 5 Mar. 13 9 | Mar. 5 | Mar.19] 15 
time some change takes place also in the semihardy buds, for the 
period of development is shortened from 16 to 1o days. From 
January 24 throughout the remainder of the winter the degree of 
dormancy continues to decrease, and collections made on March 5 
show that the length of time required for anthesis has been short- 
ened to g days in the case of Stella and Tonka, and to 15 days 
in the case of Assiniboine. It must not be inferred that the time 
at which the break in dormancy occurs can be assigned to any 
particular day, for undoubtedly the changes involved proceed 
slowly, and development is initiated gradually. January 24 is em- 
phasized as the time when the first evidence of a break in dor- 
mancy was observed, while in reality the changes involved may 
