Jan. 20, 1923 
After-Ripening and Germination of Apple Seeds 
159 
30° C., about 50 per cent of these seeds were wholly decayed, and the 
rest were entirely obscured by a dense mass of all sorts of micro-organ¬ 
isms. Observations a few days after first putting these seeds into the 
incubators indicated that in general only those seeds decayed in which 
the inner coat was injured. At the end of 50 days the outer coats of 
all the seeds were so softened and decayed that they were easily rubbed 
off between the thumb and fingers in water. After thorough washing, 
these seeds, with the outer coats removed but the inner coats intact, 
were returned to the incubators where almost all of them remained 
in good condition during the following 4 months, although during a 
part of that time they were on moist blotters throughly infected with 
organisms of decay. 
SUMMARY 
(1) Apple seeds, when taken from the apples at their maturity, are 
incapable of germination. Etherization or the use of alternating tem¬ 
peratures does not bring about germination. 
(2) The dormancy is resident in the embryo. Naked embryos fail to 
germinate normally. 
(3) Apple seeds acquire the power to germinate—that is, they after- 
ripen, in a few months when kept moist at a temperature between 5 0 and 
io° C. They also after-ripen within the fruit in commercial cold storage 
(o° C) or in a cold cellar. They do not after-ripen in dry storage or 
when kept moist at 20° C. or at a higher temperature. 
(4) The relation of oxygen to after-ripening was not determined, but 
apparently a good supply of oxygen is always present within the core of 
the apples when they are kept at low temperatures. 
(5) After-ripened seeds will germinate completely in a few weeks in an 
ice box if the temperature is not too low. They germinate fairly well at 
20 0 C., but not as well at 25 0 . The optimum temperature for their ger¬ 
mination seems to lie somewhere between ro° and 20° and to vary accord¬ 
ing to the condition of the seed or possibly according to % the variety of 
apple. 
(6) There seems to be a tendency for the after-ripened seeds to go into 
a state of secondary dormancy when kept under conditions which pre¬ 
vent their germination. 
(7) The commercial practice of layering apple seeds out of doors over 
winter is not necessary in order to bring about their complete after¬ 
ripening and germination. 
(8) Removal of the outer seed coat has no apparent effect on com¬ 
pletely dormant apple seeds. Removal of both seed coats causes some 
of the dormant embryos to make feeble growth, but these do not produce 
normal seedlings. 
(9) Removal of the outer coat or of both coats accelerates the germi¬ 
nation of after-ripened seeds. 
(10) Removal of the coats from seeds which have been incubated for a 
long time under germination conditions, but at a temperature too high 
for complete after-ripening, may induce prompt and vigorous germina- 
nation. Some phases of after-ripening must therefore take place at 
these higher temperatures, while others are dependent upon a lower 
temperature, or upon the removal of the coats. 
(11) The inner seed coat is very efficient in preventing decay of the 
seeds, but the outer seed coat, with its open hilum, is of little use in this 
respect. 
