THE FRUIT 153 



The various terms which define the position or direction of the 

 ovule (erect, ascending, etc.) apply equally to the seed : so also the 

 terms anatropous, orthotropous, campylotropous/ etc., as 

 already defined, and such terms as 



HiLUM, or scar left where the seed stalk or funiculus 

 has fallen away, or where the seed was attached directly 

 to the placenta if there was no seed stalk. 



Raphe, the line or ridge which runs from the hilum 

 to the chalaza in anatropous and amphitropous seeds. 



Chalaza, the place where the seed coats and the kernel 

 or nucellus are organically connected, — at the hilum in orthotropous 

 and campyloti'opous seeds, at the extremity of the raphe or tip of 

 the seed in other kinds. 



MiCROPYLE, answering to the foramen or orifice of the ovule. 



ECOLOGY OF THE FRUIT AND SEED AS REGARDS DIS- 

 SEMINATION 



337. The word dissemination here signifies the scatter- 

 ing of the seeds. In a vast number of cases not only the 

 seeds, but the entire fruits, are dispersed, the pericarp fur- 

 nishing the same protection to the seed that it jDrovided 

 during the period of ripening, and furthermore aiding 

 directly by its construction in the transportation or even 

 in the planting of the seed. 



338. The need of seed dispersal is plain, both for the 

 parent plant — which should not be crowded by its own 

 offspring — and for the interests of the seedlings them- 

 selves. That an advantage is to be won through wide dis- 

 tribution of seed is shown by the fact that the seed or 

 the fruit is, in most species, adapted to the special work 

 of dissemination. 



339. The agents of dissemination are wind, water, and 

 animals. But a considerable number of plants are quite 

 independent of external aid, being provided with special 

 mechanisms for throwing their seeds to a distance. 



340. Structures to accomplish dissemination through the 

 agency of the winds are exemplified by the wings of the 

 Elm and Maple fruits (Figs. 265, 266), the plume of 



1 For these terms see the section on the ovule, § 280. 



