58 BOTANICAL GAZETTE [JANUARY 
seed, but these changes, as has been outlined, are quite different 
from those occurring during after-ripening. Seeds ready to 
germinate (after the coat is cracked and their water content 
increased to 52 per cent) are killed by an exposure to — 5° C. 
6. The juniper seed has a dormant embryo that must after- 
ipen before germination. After-ripening occurs at temperatures 
between o* 1° C. and 10° C., although fastest at about 5° C. 
: “y7. The changes that accompany after-ripening of the juniper 
seed at 5° C. were found to be as follows: (1) rather rapid and com- 
‘plete imbibition, followed by a steady slow decrease in water con- 
tent during after-ripening or until near germination; (2) increased 
H* ion concentration, especially of the embryo; (3) an increment 
_ of titratable acid; (4) a steady and enormous increase in the degree 
_ of dispersion of the stored fat; (5) decrease in the amount of stored 
_ fat and protein, with an increase of sugar content and the first 
appearance of starch; (6) the translocation of food in the form of 
fat or fatty acids from endosperm to embryo; (7) a seven-fold 
increase in the amino acid content, and a complete disappearance 
of histidine from the endosperm; (8) an increase of soluble proteins, 
with a marked hydrolysis of the stored proteins: (9) slight growth 
of embryo; (10) very slight increase of the respiration intensity; 
(11) increased respiratory quotient; (12) decreased intramolecular 
respiration; (13) a doubling of the catalase activity; and (14) the 
fe rise in vigor of seeds as shown by their resistance to fungal attack. 
> 8. In conjunction with after-ripening at 5° C., desiccation seems 
/to be the only promising means of shortening this after-ripening 
\period. 
g. The time at which the hypocotyl breaks through the nucel- 
lus was fixed as the end of after-ripening and the beginning of 
germination. 
10. Neither the resting nor the after-ripened juniper seeds 
yield more than about 1 per cent germination at temperatures 
above 15°C. Seeds after-ripened at 5° C., then placed at 10° C., 
germinate slower than those left at 5° C. When after-ripened 
seeds are transferred from 5° C. to temperatures above 15° C. they 
are thrown into a state of secondary dormancy. Hence these 
seeds require a low temperature for germination as well as for 
after-ripening, and therefore no seed should be transferred to 
