418 



Mr. F. Kidd. The Controlling Influence of 



without grass had germinated and sprouted vigorously. The results 

 obtained are shown in the photograph and in the following table. 



Eesults obtained with Brassica alba, seeds in pit over Grass and in Control Pit 

 without Grass after seven days. 



Table VII. — Eesults obtained with Brassica alba Seeds, planted (1) in Soil 

 over Decaying Green Grass, and (2) in Ordinary Soil. 



Depths. 



Germinations out of 25 seeds after 7 days. 



Over decaying grass. 



Control in ordinary soil. 



inches. 

 3 

 6 

 9 



3 just sprouted 

 







25 well grown. 

 25 



25 ■ 



Thus 72 out of the 75 Brassica alba seeds planted in soil over decaying 

 grass were inhibited in conditions which may be supposed to occur some- 

 times in the soil {eg., in the ploughing in of green crops*). These seeds 



* The case of heavily dunged land would also suggest itself. Boussingault and Lewy, 

 in a large series of analyses of soil air, found 10 per cent, of C0 2 in manured soil 10 days 



