Carbon Dioxide in Maturation, etc., of Seeds. 615 



germinating conditions, are capable of immediate germination. In this and 

 similar experiments it was noticeable, especially in the case of peas, that 

 removal of the testa greatly increases the rate of this germination. The 

 following experiment was typical : — 



Table V. — Increased Eate of Germination in Maturing Seeds of Peas 

 when Testa is removed. 





Germinations. 





Description of seed. 







Remarks. 



3rd day. 



8th day. 



Peas fresh from the pod (10 with 

 testa) 



Peas fresh from the pod (10 without 

 testa) 





 3 



4 

 8 



The testas of the six not growing 

 were removed on the 8th day. 

 All these six then sprouted 

 within two days. 



(2) Further experiments to test the power of the embryo of the ripening 

 bean and pea, before drying has commenced, to grow without the addition of 

 moisture, were necessary. To this end 10 bean embryos taken from seed in 

 immature condition were placed in glass tubes closed at both ends with 

 bored rubber corks. They were placed at such distances as to avoid 

 contact with each other. 



In six days the radicles of all had sprouted ; similar results were obtained 

 with embryos taken from immature pea seeds. 



These experiments were repeated another year with confirmatory results. 



The bare embryos germinate readily in the above conditions. In parallel 

 experiments made with whole immature seeds, the presence of the testa still 

 intact was found to retard sprouting constantly. This retarding effect of the 

 testa was more marked in these cases where no water was added to the green 

 seeds from the pods than in the experiments above, in which such seeds were 

 germinated in the ordinary way on damp sand. In connection with this 

 action of the testa it is of great interest to find that Guppy, in a recent 

 book containing the results of a wide series of studies upon seeds, remarks 

 that " it is noteworthy that the viviparous habit is associated with the 

 absence of seed coats." 



(3) Experiments with germinating beans after complete air-drying in the 

 laboratory showed that, at the moment of sprouting, these seeds might 

 actually contain less water than they did when originally removed from the 

 pod. These experiments were conducted both with whole seeds and with 



