REPRODUCTION 109 



with two large but delicate cotyledons, containing 

 practically no reserves. 



We have next to inquire what is the significance 

 of this difference between the two types of organism ? 

 The explanation is again to be found in the fact that 

 the animal is a motile and the plant a fixed organism ; pistritm- 

 for it is during the hibernating period that the seed 

 is distributed. Each parent may produce thousands 

 of seeds, and manifestly it would never do to sow 

 them in the immediate vicinity of 

 the parent ; there would be no room 

 for them to take root, much less find 

 nourishment. They must be dis- 

 persed, and it is manifest that there 

 is more likelihood of their surviving 

 if they be thoroughly protected 

 and in a quiescent condition while 

 dispersal is being effected, than if 

 they be in an actively germinating FlG 56 Fruit O f 

 condition. Cherry : a, succu- 



The seed being, like its parent, len * la y er ; 6 > hard - 



non-locomotorv, must be aided in ened lay^r c > 

 j. , -. ?y i j testa; a, embryo, 



dispersal, and the agents employed 



are, in the main, four, viz., wind, water, animals, and 

 ejaculatory efforts on the part of the parent plant. 



Let us glance at an example of each of these modes of 

 dispersal. In the case of wind it is obvious that the 

 seeds must be light and buoyed up by something in the 

 nature of a parachute. Thus we have the wings on 

 the fruits of the maple and of the ash (Fig. 53), and niustra- 

 the hairs on the seeds of cotton and of the willow tions - 

 (Fig. 54). It comes to the same thing, in the end, 

 whether single-seeded fruits be dispersed or whether 

 the fruit wall opens and the individual seeds be 

 dispersed. Hence the " float " may be developed 



