616 



Mr. F. Kidd. The Controlling Influence of 



the embryo alone. The following are representative examples taken from a 

 series of experiments : — 



Table VI. — Showing that Beans germinated after Complete Air-drying may 

 actually contain at the moment of sprouting less water than they did 

 when originally removed from the fresh green pod in the last stages of 

 maturation before drying on the plant had commenced. 





Original weight of 10 beans when 

 removed from fresh pods before 

 natural drying had commenced. 



"Weight of the same 10 beans at 

 the moment of sprouting during 

 germination on damp sand after 

 complete air-drying. 





grm. 



grm. 





27 -7 



22 -6 



Embryos alone 



24 1 



21 -6 



22 -0 



20 -1 



From these experiments it would appear, therefore, that neither lack of 

 water nor any physiological insufficiency in the embryo can be regarded 

 as the factor limiting germination in the maturing seeds of peas and beans. 



Finally, the action of the testa as a retarding influence on germination has 

 to be noted. In addition to experiments already given with seed still 

 immature, the following experiments were made with dried seeds : — 



Table VII. — Retarding Influence of the Testa in Germination of Dried Seeds. 





Water uptake 

 after 24 hours 



Germinations. 



Description of seeds. 



in percentage of 

 original 

 dry weight. 



1st 

 day. 



2nd 

 day. 



3rd 

 day. 



4th 

 day. 



5th 

 day. 



9th 

 day. 



Peas 8 days dried in air after removal 

 from pod, temp. 18-14° C. — 



139 











1 



5 









112 











5 



7 







Dry beans — 



10 with testas 



116 















4 

 8 



9 







119 







1 



3 



10 





Dry beans — 



100 











1 



3 





8 



10 without testas 



116 







10 



10 



10 





10 







In the above Table the retarding influence of the testa in the germination ' 

 of seeds after drying is well marked. 



(b) Direct Estimation of the CO2 Content of Maturing and Germinating 

 Seeds. — An enquiry is strongly suggested as to how far the non-germination 



