Treatment of Cotton Seed 
57 
When a comparison is made of the results of the tests with lots 3 and 4 
in which treated and untreated seed were germinated with testas intact, 
it is apparent that the rate of germination of the treated seed exceeded that 
of the untreated seed. At the end of the 45-hour period, 23 of the treated 
compared with 18 of the untreated seeds had germinated, and 12 hours 
later the relation was at 87 to 65. At the expiration of 91 hours, the germ¬ 
ination of lot 3 still exceeded that of lot 4 slightly both in regard 
to number of seeds germinated and to the average length of the radicles 
of the seedlings. 
In Experiments 2 and 3 the seed used had been treated in the seed¬ 
treating machine described in another section of this paper. Here, again, 
the rate of germination of naked embryos of treated seed was retarded 
in comparison with that of decorticated untreated seed; and, when seed 
were put to germinate with testas intact, the treated seed germinated 
more quickly than the untreated. Experiment 4 was exactly like Experi¬ 
ment 3 except that the sterile blotters were permitted to become slightly 
dry by standing in the laboratory for a time before the seeds were put 
to germinate. Under this condition of less rapidly available moisture the 
number of treated seeds which germinated exceeded the number of untreated 
so slightly as to be negligible yet the retardation of germination due to 
the effect of the treatment on the embryos was completely counterbalanced 
by the increased permeability of the testas of the treated seeds. 
The removal of the seed coat permitted much quicker germination of both 
treated and untreated seed than when seed coats were intact, but the 
retarded rate of germination of the treated embryos was completely masked 
and even overcome by the restriction to germination imposed by the intact 
seed coat of untreated seeds. It is apparent that while the treatment 
affected the embryo in such a way as to prolong the period required for 
germination to begin it also produced a profound change in the testa in¬ 
creasing its permeability and more than compensating for the less prompt 
start of the treated embryos into activity. 
The exact nature of this increase in impermeability of the testas of 
treated seeds has not been determined. t It may be that fissures form in 
the seed coat as the result of heating and thus a more ready access of 
water to the embryo is provided as suggested by Detmer. 15 Denny 14 found 
that lipoids, tannins, and pectic substances were factors in determining 
the permeability of the coats of certain seeds. He found that the permea¬ 
bility of the seed coat of Arachis liypogea could be increased 28 to 50 per 
cent by heating the seeds in dry air at the temperature of boiling water. 
A much greater increase of permeability occurred when the seed coats 
were extracted for five minutes in boiling water. 
The experiments described above may be summarized in the following 
words: The effect of desiccating cotton seed at relatively low temperatures 
varying from 40 to 60° C. for various periods of time has been studied as 
a means of conditioning the seed to endure without injury, temperatures 
