SECT. I. CONDITIONS. 



is fully ripe, as in the case of the Coffee-bean ; 

 which will not germinate unless it is sown within 

 five or six weeks after it has been gathered. 



But most seeds if guarded from external injury 

 will retain their germinating faculty for a period of 

 many years. This has been proved by the experi- 

 ment of sowing seeds that have been long so kept ; 

 as well as by the deep ploughing up of fields that 

 have been long left without cultivation. A field 

 that was thus ploughed up near Dunkeld, in Scot- 

 land, after a period of forty years' rest, yielded a 

 considerable blade of Black Oats without sowing. 

 It could have been only by the plough's bringing 

 up to the surface, seeds that had been formerly toa 

 deeply lodged for germination. 



SUBSECTION II. 



Exclusion of Light. The second condition is, 

 that the seed sown must be defended from the 

 action of the rays of light. This has no doubt 

 been long known to be a necessary condition of 

 germination, if we regard the practice of the har- 

 rowing or raking in of the grains or seeds sown by 

 the farmer or gardener as being founded upon it. 

 But it does not seem to have engaged the notice 

 of men of science, or to have been proved by direct 

 and intentional experiment till lately. The first; X per 

 direct experiments that were instituted on this sub 

 ject, are those of Ingenhoutz,* who found 

 * Expcr. sur. la Veg. vol. ii. 



