268 STRUCTURE AND VITAL PROCESSES OF PLANTS 



The outer part (exocarp) may be smooth and shining, as in 

 the Chilli ; or glaucous, as in the Mango ; or covered with sting- 

 ing hairs, as in Mucuna pruriens (Kan. Nayisonaguir'Jia?. ^s'ayi- 

 kuruna) ; or prickly, as in the Thorn-apple. All these qualities 

 serve as protections from damp or from the aggressions by 

 animals, or they are a means for the attraction of animals which 

 would scatter the seeds. 



The middle part (^mesocarp) is fibrous in the Cocoanut, but 

 soft and juicy in many other fruits. The pulpy mass remains,' 

 however, sour or bitter during the period of growth and sweetens 

 only when ripe. This quality, likewise, serves as a means for 

 the scattering of the seeds by animals. 



The inner part {endocarp) in these fruits is hard like stone, 

 called pyrene, and forms a very strong protective covering to 

 their seeds. In other fruits it forms a skinny membrane lining 

 the inner cavity of the fruits in which the seeds rest, or the 

 partitions of the fruit, as in the Orange. 



2. The Seed. — While the seeds grow and require nourish- 

 ment, they are attached to the placenta by a cord, called funicle. 

 When they are mature, the funicle withers, and a scar, called 



lulum, is left on the seed. 



The seed consists of the embryo and 

 its protective coats. The outer coat, called 

 testa, has, by the side of the hilum, a small 

 hole, the micropyle, by which the pollen- 

 tube entered the ovule for fertilization 



Fig. 258.— Seed of , r»-r^^ rm < , • nil 



„ , , , (page 2o9). The testa is usually hard, 



Horse gram (enlarged). \i o / ^ ^ 



sometimes possessing projections into the 

 interior ("ruminating testa") as in the Nutmeg and in the 

 ('ustard Apple, sometimes developing appendages for dissemina- 

 tion, as in .Madar, Eignonia, and Lagcrstra'Uiia. In the Pome- 

 granate it is juicy. A growth of spongy tissue is found on the 

 testa of certain seeds. If it appears round the micropylc, as in 

 the Castor-oil seed, it is called caruncle; if it originates from 

 the attachment of the funicle, it is termed aril (Nutmeg). 



The inner coat, cjilled tefjmen, is absent in many seeds. It 

 may be seen in the Castor-oil seed. 



