1913] ECKERSON—AFTER-RIPENING 287 
necessary before germination, LaKon calls this ‘‘ Vorkeimung” 
instead of ‘‘ Nachreife.”’ 
Many methods have been used by different workers in the 
attempt to shorten the resting period of buds and bulbs. The 
first of these is JOHANNSEN’S (30) treatment with ether. He found 
that growth could be hastened at the beginning of and near the end 
of the resting period, but not in the middle period. Motiscu (40) 
immersed shoots in water at 35° C., and the buds opened earlier than 
those on untreated shoots. IraKtioNow (23) finds that the warm 
bath increases respiration only in the first days, then the respi- 
ration curve falls to its original height. Mi.iter-THuRGav and 
SCHNEIDER-ORELLI (42, 43) used the warm bath method to hasten 
the germination of potato tubers, and lily of the valley bulbs. 
They find the sugar content increased by the warm bath, but this 
is immediately used by the increased respiration. Unless the 
bulbs are kept at a high temperature, there is no lasting effect. 
Zero temperature increases the sugar content and the respiration; 
injury produces a slight increase in sugar content. They do not 
believe that hastened growth in these cases is due to increased 
sugar content, but rather that the high temperature has some effect 
on the protoplasm. CHRISTENSEN (3) made chemical analyses of 
resting and growing bulbs, but found no appreciable differences. 
He concluded that the slow growth of resting bulbs was not due 
to lack of soluble food materials. 
WEBER (53) and JESENKO (27) found that injury to the buds 
hastens their development. Later, JEsENKO (28) found that 
the shoots from these buds were abnormal. Shoots immersed in 
dilute solutions of alcohol, H,SO,, and other substances, develop 
normally and more rapidly than untreated shoots. Laxkon (37) 
forced the development of winter buds by standing the cut ends 
of shoots in Knop’s solution. Mottscu (41) has recently found 
radium emanations effective. 
All these various methods shorten somewhat the rest period of 
bulbs and winter buds. Little has been done to determine what 
is the limiting factor to growth in these cases and what internal 
change is produced by the external application. 
CROCKER (4, 5) found that the long period required for germina- 
