PROPAGATION. 31 



factory ; and we have likewise found pure, dry sand use- 

 ful for the same purpose. 



Warmth and moisture are the principal agents that 

 induce germination, but a superabundance of either 

 just as readily causes decay. The moment seeds are 

 placed in contact with moisture, they absorb oxygen, 

 the starch and other compounds are decomposed, carbon- 

 ic acid is given off, and the development of the em- 

 bryo plant commences. It is also necessary that a 

 certain degree of heat should attend the operation, and 

 the amount varies in different species of plants ; there- 

 fore no definite rule can be given, but the judgment 

 of the propagator must be exercised to prevent an excess, 

 and, what is equally requisite, preserve a sufficient amount 

 of warmth in the soil. 



Most seeds of the Coniferge germinate easily, but the 

 young plants are so sensitive to adverse circumstances, 

 such as dampness, heat, drought, etc., that they are ex- 

 ceedingly liable to be lost before forming their true leaves. 

 This is the critical point in raising seedlings ; for, after 

 the plumule has developed into leaves, and the radicle 

 has formed sufficient fibres to nourish the young plantlet, 

 the danger is chiefly past and less care is required in its 

 growth. 



Seeds should always be sown thinly and evenly for sev- 

 eral reasons. If the young plants stand too close to each 

 other, a portion are shaded, which not only draws them 

 up with long stems, but in many cases destroys them en- 

 tirely. The stronger also abstract the nutriment from the 

 soil, to the detriment of the weaker plants, and the latter 

 very soon become stunted and often worthless. 



A high temperature is decidedly unfavorable to the 

 growth of seedling Conifers, and, for this reason, the seed, 

 when planted in the open ground, should either be sown 

 in the autumn, or, as some of our best propagators now 

 prefer, as early in the spring as the frost will allow. 



