1921] PACK—JUNIPERUS 33 
As it has been impossible to dispense with this rest period in all 
cases, many substances have been used to reduce dormancy and 
force seeds to germinate. Concentrated sulphuric acid has been 
used by HitTNer and K1nzeE (17), Rostrup (32), and others with 
positive results. Among the salts Rose (31) noted that the sul- 
phates and nitrates were the better forcing agents. Hydrogen 
peroxide and increased oxygen pressure forced the germination of 
Xanthium seeds (5). Wounding and treatment with ether stimu- 
lated the germination process (3). Light has been found to force or to 
inhibit germination depending on the seed (12, 20).. The New York 
Experiment Station (24) and many others have shown that desic- 
cation improves the germinating power of corn. The hot bath 
has been used with success on some seeds (4). Alternating tem- 
peratures have been used to force grass seeds in the Seed-testing 
Laboratories of the Bureau of Plant Industry. With these much 
has been claimed for freezing and thawing as a forcing agent (29). 
Laxkon (21), however, found that the germination of Pinus Peuce, 
P. Cembra, P. Strobus, and P. silvestris could not be accelerated 
by treatment with dry heat, warm bath, file injury, ether, chloro- 
form, salt solutions, concentrated sulphuric, or dilute acids. 
Seeds with dormant embryos must go through a series of changes 
(after-ripening) before germination can occur (5). The after- 
ripening of hawthorn seeds proceeds fastest at 5-6° C. according to 
Davis and Rose (8). An idea of this after-ripening process may 
be gained by following the results of Lakon on a protein and 
ECKERSON (10) on a fatty seed. Laxon (22), in studying the 
changes that precede germination of Fraxinus excelsior, found 
very little increase in water absorption. From the tenth day on, 
starch accumulated in the embryo cells, with a corresponding dis- 
appearance of protein from the endosperm cells. In place of the 
disappearing protein a turbid emulsion formed, which later was 
digested. At no time did starch appear in these endosperm cells. 
The embryo doubled its length during this process of ‘‘ Vorkeimung.”’ 
EcKERSON (10) studied the changes occurring in the hawthorn 
seed during after-ripening, and reported an increasing acidity 
and water absorbing power of the dormant organ. The catalase, 
peroxidase, and oxidase activity increased as after-ripening and 
