The Role of the Seed-coat in Relation to the 
Germination of Immature Seed. 
BY 
FRANKLIN KIDD 
AND 
CYRIL WEST. 
With six Tables and one Chart in the Text. 
I N previous papers (9 and 10 ) it has been shown that the germination of 
seeds of Brassica alba , sown in the presence of certain percentages of 
carbon dioxide, can be completely inhibited, and that this inhibition of ger- 
mination is often maintained indefinitely after the removal of the seeds to 
air. This is a remarkable phenomenon, and it is the more striking in that 
seeds rendered dormant by carbon dioxide show no signs of injury when 
finally brought to germination even after the lapse of twelve months. So 
far the authors have found only two certain methods of destroying the 
dormant condition into which the seeds are thrown by the carbon dioxide 
treatment. One method is to redry the seed, the other method is to remove 
the testa without drying. 
In the present paper results are recorded which show that a condition 
of dormancy, similar in many ways to that produced when dry mature seeds 
of Brassica alba are sown in the presence of carbon dioxide, may be 
observed when immature seeds of this plant are sown immediately after 
removal from the parent and before the natural drying process has begun. 
Experiments with Brassica alba. 
The seeds in the following experiments were obtained from plants 
grown in the Botanic Gardens, Cambridge. The different degrees of ripe- 
ness of the seeds were as follows : 
A. Green-ripe: Seeds fully swollen; still quite green; 50 per cent, to 
80 per cent, of the dry weight of ripe seeds. Siliquas bright green. 
B. Yellow-ripe : Seeds fully swollen ; yellow in colour ; of practically 
the same dry weight as fully ripe seeds. Siliquas still moist ; begin- 
ning to turn yellow. 
The germination results are set forth in the following tables (Tables 
I-IV) and chart. Yellow-ripe seeds with the testa intact, when sown 
[Annals of Botany, Vol. XXXIV. No. CXXXVI. October, 1920.] 
