154 THE PRINCIPLES OF FLORICULTURE 



frames, so that a strong, sturdy growth results. If sown 

 too early in greenhouses, the plants show a weak, spin- 

 dling growth. 



When carnations are propagated from seeds for the 

 production of new varieties, the crossing is usually begun 

 in November. The resulting seeds are sown as soon as 

 they have matured. The plants may then be planted in 

 the field early in the season and the flowering period will 

 begin there. The propagator then forms an opinion of the 

 value of the result of the cross and thus determines which 

 plants promise well for further trial under glass. 



116. Dormant period of seeds. Each seed contains an 

 embryo, or vital part. It also contains reserve food to 

 nourish the embryo in germination or until it is able to 

 get nourishment from the soil. The dormant period 

 varies with different species. As a rule, seeds which con- 

 tain large quantities of oil lose their germinating powers 

 much more quickly than do those which contain starches. 

 To preserve seeds, it is necessary that they be kept from 

 moisture. With the application of heat and moisture, 

 the enzymes, or those agents in the plant cell which have 

 the power of changing starches to sugars, become active. 

 The sugars are transferred from cell to cell, stimulating 

 protoplasm into activity so that cell division goes rapidly 

 on and growth results. This accomplishes what the 

 flower-grower knows as germination of seeds. 



117. Requisites for germination. As has been stated, 

 two of the principal requirements of seeds for germina- 

 tion are heat and moisture. They also require the free 

 oxygen of the air. 



The amount of water required and the degrees of 

 temperature necessary for seed germination vary accord- 

 ing to the species. Some seeds germinate in a com- 



