CH. I.] SOWING. 41 



of their parent plant, that the oxygen absorbed by 

 the seeds combines with a portion of that extra carbon, 

 and is emitted in the form of carbonic acid. These 

 are the attendant phenomena, but we can penetrate 

 the mysteiy no farther. 



I have never been able to discover that light has 

 any injurious influence over germination, and in 

 those experiments apparently proving the contraiy, 

 due care was not taken to prevent the seed being 

 exposed to a greater degree of dryness as well as to 

 light. If seed be placed on the surface of a soil, 

 and other seed just below that surface, and care be 

 taken to keep the former constantly moist, it will ger- 

 minate just as speedily as the bui'ied seed, and if ex- 

 posed to the blue rays only of the spectrum, by being 

 kept under a glass of that colour, even more rapidly. 



M. Saussui'e found that when the dii'ect rays of 

 the sun were intercepted, though light was admitted, 

 seeds geiTiiinated as fast as when kept in the dark^. 



Therefore the object of so^^Tng the seed below the 

 surface, is for the purposes of keeping it in a 

 state of equable and salutary moisture, as well as to 

 place the radicle in the medium necessary for its 

 gro^vth into a root, immediately it emerges from the 

 integument of the seed. 



A seed placed in a situation where it is supplied 

 with the desirable degrees of heat, moisture, and air, 

 * Recherches sur la Vegetation, 23. 



