242 ON PROPAGATION BY SEED. 



trated with moisture. This method is very well suited for sowing on a 

 large scale ; but as the seed often perishes during the winter, and the earth 

 becomes soddened, or thickly covered with moss, the preferable way for 

 valuable seeds which are to be raised in the open air, is to sow them in the 

 spring, after they have been soaked for some days previously in warm water 

 (Regel in Gard. Mag. for 1841, p. 485). Seeds that are to be raised under 

 glass, with the aid of artificial heat, may be sown at any time. 



554. The period necessary to complete the process of germination varies in 

 different seeds, though all attendant circumstances may be alike. The 

 grasses generally vegetate most rapidly, and they are quickly followed by 

 some of the cruciferous and leguminous plants; umbelliferous plants are 

 generally slower, and rosaceous plants still more so. Adanson gives the 

 following table of the period of germination in several seeds tried by him- 

 self in France. 



Days. Days. 



Wheat, millet 1 



Strawberry blite, beans, mustard, kidney 



beans, turnips, radishes, and rocket g 3 



Lettuce, and aniseed . . . . 4 



Melon, cucumber, gourd, and cress . 5 



Horse radish, leek . . . 6 



Barley 7 



Oiache 8 



Purslane 9 



Cabbage 10 



Hyssop 30 



Parsley . . . . 40 or 50 



Cow-wheat, almond, chestnut, peach, 



and peony . . . One Year 



Rose, hawthorn, hazel, nut and 



cornel . . . . Two Years 



(Fam. des Plantes, vol. I. p. 84.) The same author found that the seeds 

 which germinated in twelve hours in an ordinary degree of heat, might be 

 made to germinate in three hours by exposing them to a greater degree of 

 heat ; and that seeds transported from the climate of Paris to that of Senegal, 

 have their periods of germination accelerated from one to three days. On 

 the same principle seeds transported from a warmer to a colder climate 

 have their period of germination protracted till the temperature of the 

 latter is raised to that of the former. The seeds of annuals generally ger- 

 minate quicker and with more certainty than those of perennial plants ; 

 and they generally retain their power of germination much longer. 



555. The quantity of moisture most favourable to germination must depend 

 on various circumstances, such as the degree of heat with which it is accom- 

 panied, the vital power of the seed, and the nature of the species. The seeds of 

 aquatic plants vegetate when immersed in water, and the plants live, and attain 

 maturity in that element ; but those of land plants, though they will vegetate in 

 water, yet if the plants be not removed immediately after germination, they 

 will become putrid and die. In general, the most favourable degree of mois- 

 ture for newly sown seeds, is that which a free soil holds in its interstices. 

 Clayey soil will retain too much moisture for delicate seeds, and sand too 

 little ; but an open free loam will attract and retain the proper quantity for 

 all seeds, excepting those which are very small and very delicate ; and for 

 these a mixture of peat, loam, and fine sand, will retain just moisture 

 enough, and no more. With all delicate seeds it is better rather to have too 

 little moisture than too much ; and with all seeds whatever, it is of great 

 importance to preserve the degree of moisture uniform. For this purpose, in 

 the open garden, newly sown delicate seeds are shaded or covered by different 

 means, such as sowing them on the north sides of hedges or walls, interpos- 

 ing hurdles placed upright or horizontally, between the sown seeds and the 

 sun, covering with mats, or branches, or litter, or, in the case of very small 



