PROPAGATION OF PLANTS. 189 



which hang until swallowed by birds, and sprout more 

 freely after having undergone the digestive process. 

 Some exotics of a hardy character likewise succeed best 

 when sown at the time the seed falls, vegetating in 

 autumn, growing slowly through the colder months, and 

 progressing rapidly when spring opens. Others coming 

 from a different climate, starting into growth in autumn, 

 would perish during the winter months; but kept and 

 sown when the temperature of the air and soil in spring 

 is suitable for vegetating them, they will advance rapidly 

 as the weather becomes more and more favorable to 

 growth. In some cases, where it might be best to sow 

 at the natural period, if the aim was simply to continue 

 the species, other motives render it necessary to sow at 

 other times. A succession of flowers or a continued sup- 

 ply of vegetables during the season may, in the case of 

 annual or biennial plants, make repeated sowings at 

 proper intervals desirable. 



Trees and shrubs it is well to sow, if practicable, at the 

 natural period, but it is desirable that the seedlings should 

 not make their appearance above ground until a favor- 

 able season for growth. This is most readily secured in the 

 case of seeds that do not keep well dry, by stratification 

 or mixing them with soil in autumn, but not encouraging 

 growth until spring. This is done by placing a layer 

 of seeds upon the surface of the soil, then a layer an inch 

 or two thick of sand or light soil, and so on, the whole 

 being laid so as to form a cone, over which is spread a 

 covering of soil to protect from wet and frost. This should 

 be done where least likely to invite the attacks of mice 

 and other animals. Small quantities of seeds of this kind 

 may be stratified in boxes and flower pots, covered from 

 rats and mice and placed in a cool situation until spring. 

 Holly seed requires to be kept thus two years. When 

 vegetation begins to take place, the seeds, still mixed 



