Treatment of Cotton Seed 
65 
and juniper 46 are dormant and must pass through a period of after-ripening, 
the time of which may be shortened by appropriate treatments before 
germination can take place. 8 , 13 , 19 . On the other hand, delayed germination 
in Xanthium 8 , 46 and Avena fatua 1 is due not to dormant embryos but 
primarily to seed coat structures preventing the entrance of oxygen; in 
Axyris amaranthodides and Chenopodium ablum 8 and Lathyrus maritimus , 52 
to seed coats retarding or preventing the entrance of water; and in Iris, 8 
Alisma plantago, 11 other water plants, 9 and Diospyros Virginia , 5 to the 
great strength of the seed coat which mechanically prevents swelling of 
the embryo before the latter has imbibed sufficient water to permit germ¬ 
ination. With Ilex 37 there obtains a combination of conditions falling in 
the two general categories mentioned above. The embryos are not dormant 
but very immature and require a long period of growth before germination 
occurs but even then the weak hypocotyl is unable to penetrate the woody 
pericarp until the latter has decayed sufficiently. 
Seeds of certain plants which are capable of immediate germination 
may be thrown into a condition of secondary dormancy. Kidd 10 , 41 subjected 
seeds of Brassica alba to high partial pressures of C0 2 and found that the 
treated seeds became dormant and remained in that condition indefinitely 
after removal from the inhibiting C0 2 pressures. The dormant condition 
could be broken only by redrying and rewetting or removal of the testas. 
Crocker 7 cities other instances in which secondary dormancy has been im¬ 
posed on seeds by treatments which induced restrictive seed coat changes. 
However, in the cases of secondary dormancy induced in Brassica alba 
seeds by Kidd and in the cases cited by Crocker the dormant condition was 
induced while the seeds were in the moist condition favorable for ger¬ 
mination. On the contrary, the secondary dormancy exhibited by the cotton 
seeds described above was induced by excessive drying in desiccators, and 
is more nearly comparable to the wide-spread hard shell condition charac¬ 
teristic of so many of the Leguminoseae but found in certain other fam¬ 
ilies, among which are the Malvaceae, the family of which cotton is a 
member, Guppy. 28 The writer has found the hard-shell condition of cotton 
seeds occurring naturally in only one instance. Some of the seeds used 
by the writer from the 1924 crop had come to maturity during a season 
unfavorable for the best development of cotton seeds and among these one 
seed in a lot of 100 was occasionally found which did not germinate because 
of its hard shell condition. According to Toole and Drummond, 59 “If the 
seeds dry out until the moisture content is between five and six per cent, 
there is a marked development of ‘hard seeds’ which fail to take up water 
at all.” A similar hardshell condition which retards or prevents germina¬ 
tion of beans was described by Gloyer 23 in 1921, who ascribed the condition 
to extreme drying while stored in artifically heated rooms or when ripening 
occurs in dry, hot weather. 
