VII] PLANT POPULATION 111 



falls upon it. In the case of the spores of Mosses or 

 Ferns the store within the single-celled germ is small 

 indeed, but the grave risks which consequently attend 

 their germination are neutralised in great measure by 

 the enormous number of the chances of success. In 

 this lottery the proportion of prizes to blanks is small, 

 but the issue of tickets is very large. In the seed- 

 bearing plants the store that accompanies each germ 

 varies greatly, from that of the minute seeds of an 

 Orchis or Rhododendron with their exiguous store, 

 to the huge supply carried in the Coco-nut. In the 

 former cases the seeds are very numerous : in the 

 latter a solitary large seed is matured from each 

 flower. In the case of large seeds the issue of lottery 

 tickets is not great, but there is a reasonable pro- 

 bability of each bringing a prize. 



Obviously the mere production of germs is not all 

 that is necessary. If those of the same plant remain 

 in close juxtaposition, in cases of the large output of 

 germs, the young plants on germination would be so 

 crowded that an internecine struggle would ensue 

 between them. To have a good chance of success 

 each must be separated from its neighbours : dis- 

 semination is essential, and it Avill be effected with 

 the greatest difficulty where the seeds are largest. 

 The agencies by which this is carried out have already 

 been alluded to above (p. 98), viz. spontaneous 

 ejection, transfer by wind, and water, and by animal 



