203 



ON PROPAGATION BY SEED. 



and easiest, whereas the albumen is less capable of doing so; and hence 

 the germination of those seeds which have none, but whose interior 

 is entirely filled with the embryo and its cotyledons, as in the 

 boragineae, labiatae, composite, &c., will be more easily effected. The 

 gramineae and umbelliferae, on the contrary, possess albumen : in the 

 former, the embryo lies outside of the albumen, on which account they 

 easily germinate ; whereas, in the latter, the embryo is entirely sur- 

 rounded by the albumen, for which reason, with the exception of most 

 of the annual or biennial sorts, they are more difficult to vege- 

 tate. As these seeds cannot be cut with advantage, it is usual to sow 

 them late in autumn, with other difficult-growing sorts ; so that when 

 the universal period of germination comes, in the spring, they may be 

 sufficiently permeated 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. Seeds that are to be raised 

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



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 ; umbelli- 

 ferous 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 himself in France : 



Days. 



Wheat, millet 1 



Strawberry blite, beans, mustard, 

 kidney-beans, turnips, radishes, 



and rocket 3 



Lettuce, and aniseed 4 



Melon, cucumber, gourd, and cress . 5 



Horse-radish, leek 6 



Barley 7 



Orache , . 8 



Days. 



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 pro- 

 tracted till the temperature of the latter is raised to that of the former. 

 The seeds of annuals generally germinate quicker and with more cer- 

 tainty than those of perennial plants ; and they generally retain their 

 power of germination much longer. 



The quantity of moisture most favourable to germination must 

 depend on various circumstances, such as the degree of heat with which 



