154 
Journal of Agricultural Research 
Vol. XXIII, No. 3 
still dormant after six months, during which time they had received the fol¬ 
lowing treatments: (i) The outer seed coats were removed from all the 
seeds 3 at the end of 50 days; (2) for the next 68 days those previously at 
30° C. were given a daily alternation between 20° and 30°, while those 
previously at 20° remained at 20°; (3) both lots were then used in a 
respiration experiment which lasted two months, and in which the tem¬ 
perature was frequently changed, using temperature intervals of 19 0 to 
30°, 30° to 19 0 , 19 0 to io°, io° to o°, o° to 13 0 , 13 0 to 30°. Besides these 
temperature changes the seeds were washed in cold water between each 
two periods of the respiration experiment, or 20 times in all. None of 
these treatments had induced after-ripening or germination as had incu¬ 
bation in the ice box. 
3. Seeds of the same original lot as the foregoing, which were incubated 
for 50 days at 20° C. in intact condition, and then 68 days in the ice box 
with the outer seed coats removed, after-ripened completely during this 
time in the ice box, so that all germinated in 4 days at 19 0 . As shown 
in the preceding paragraph, seeds which were given identical treatment 
except that they were at 20° while these were in the ice box remained 
dormant. 
Seeds of the same original lot kept in dry storage for one year and then 
put to germinate at 16 0 C., 20°, and 23 0 in intact condition, with outer 
coats removed and with both coats removed, failed to germinate. With 
both seed coats removed, all embryos decayed within a week without 
showing any of the signs of life which were exhibited by living embryos 
that were not after-ripened. 3 
In the preceding paragraphs, apple seeds have been shown to after- 
ripen when kept moist in the ice box after three conditions of previous 
treatment : 
(1) Seeds incubated in the ice box soon after removal from the fruit 
and without previously being allowed to dry out. (2) Seeds stored dry 
for two months before the ice-box incubation. (3) Seeds stored dry two 
months and then incubated two months at 20° C. previous to ice-box 
incubation. In each case concurrent germination tests showed that the 
seeds had not after-ripened under any other circumstances than storage 
in moist condition in the ice box. Dry storage previous to the germina¬ 
tion test, removal of the outer seed coats, and alteration of temperatures 
during the germination test all failed to induce germination. Further¬ 
more, attempts to force germination by etherizing the seeds were not 
successful. 
We have found that seeds of another species of Pyrus, which were 
received from the Federal Horticultural Board of the United States 
Department of Agriculture, incapable of germinating when received by 
us, after-ripen in the ice box very much the same as the seeds of our 
cultivated apples. 
AFTER-RIPENING IN THE FRUIT DURING COED STORAGE 
In the cases discussed hitherto, the seeds were removed from the fruits 
and after-ripened in the ice box under good conditions of moisture supply 
and aeration, the Petri dish covers being frequently removed to facilitate 
gaseous exchanges. But this was also true of those seeds which were 
incubated at higher temperatures, at which they failed to after-ripen. 
3 For description of the seed coats and the effect of their removal see p. 157. 
