S4 GERMINATION OF THE SEED. CHAP. I*, 



ference was in the comparative lengths of the radi- 

 cles ; the radicles of such as had been made to 

 germinate in pure oxygene gas having made less 

 progress in the same period of time than the 

 radicles of such as had been made to germinate in 

 atmospheric air. 



Applica- This may be accounted for in two ways ; the 

 boniSl" oxygene in its pure state might have abstracted too 

 detrimen- g reat a q uan tity of carbon from the seed ; or the 

 carbonic gas evolved in too great abundance might 

 have been prejudicial to the developement of the 

 infant plant. For it has been found that carbonic 

 acid gas is not useful to vegetables in general, ex- 

 cept in proportion as they can decompose it ; and 

 seeds before the developement of the plumelet do 

 not seem capable of effecting that decomposition ; 

 and in short it seems that the application of car- 

 bonic acid, in almost any proportion, retards rather 

 than accelerates the commencement of germina- 

 tion.* 



Dose of It was further remarked, by Saussure, that dif- 

 ferent species of seeds require different doses of 

 oxygene to excite germination. The quantity con- 

 sumed by the seeds of Beans and Lettuce, before 

 tKe commencement of germination, seemed to be 

 equal, and was estimated at the lOOdth part of their 

 weight. But the quantity consumed before that period 

 by grains of Wheat, Barley, and Purslain, which 

 seemed also to be equal, was only about the lOOOdth 

 * Saussure sur la Vegetation, chap. i. sect. iii. 



