ANGIOSPERMS. 617 



outer layer and a pithy inner layer ; at a very early period multi- 

 cellular protuberances are developed from the innermost layer of 

 tissue of the wall of the multilocular ovary, which gradually fill up 

 the cavity of the loculi of the fruit with isolated but closely 

 crowded succulent lobes of tissue, and form in this case the pulp. 

 d. Succulent Dehiscent Fruits. The succulent but not fleshy pericarp splits and 

 allows the escape of the seeds which have usually a strongly developed testa. 



12. The term Succulent Capsule might be given to those fruits the 



succulent pericarp of which opens by dividing into lobes, and allows 

 the seeds to escape (as in the Horse-Chestnut and Balsam). 



13. The fruit of the Walnut corresponds again to the drupe; the outer 



succulent layer bursts, a stony endocarp surrounding the thin- 

 skinned seed. It might be called a Dehiscent Drupe. 



14. The fruit of Nuphar bears more resemblance to a berry, but differs in 



the bursting of the outer firm layer of the pericarp; it may be 

 termed a Dehiscent Berry] in iV. ad-vena this exposes an inner 

 coating of each loculus of the fruit, which floats for some time on 

 the water like a bag filled with seeds. 



The enumeration here given includes only the more common forms of fruits ; there 

 are a number of others which cannot be placed exactly in any of the above categories, 

 but to which no special name has been given \ 



The Ripe Seed depends, as respects its external nature, on the development of the 

 pericarp. The testa is in general thicker, firmer, and harder in proportion to the 

 softness of the pericarp, especially when this latter bursts to allow the dispersion of 

 the seeds. When, on the contrary, the pericarp is tough or woody, and encloses the 

 seeds until they germinate, as in the caryopsis, nut, drupe, and schizocarp, the testa 

 remains thin and soft, as also when the endosperm is strongly developed and very 

 hard and encloses a small embryo, as in the Date and Phytelephas. The testa of 

 the seeds of dehiscent fruits is usually covered by a distinctly differentiated epi- 

 dermis ; and it depends on the configuration of this epidermis whether the seed has a 

 smooth appearance (as in the Pea and Bean), or displays a variety of sculpturing, such as 

 pits, warts, bands, and so forth (as in Hyoscyamus, Datura, Papa-ver, Nigella, &c.). The 

 epidermal cells of the seed not unfrequently grow into hairs; cotton consists, for 

 example, of the long woolly hairs which clothe the seed of Gossypium; in some cases 

 only a pencil-like tuft of long hairs is developed, as in jisclepias syriaca. The epidermal 

 cells of some seeds, as the Plax, Quince, Plantago Psyllium, arenaria, and Cynops, contain 

 layers of cellulose which have become converted into mucilage, swell up strongly with 

 water, become separated, and envelope the seeds when moist in a layer of mucilage. 

 Pericarps which are indehiscent and which contain small seeds not unfrequently assume 

 a character closely resembling that of the testa of the seeds of dehiscent fruits; and 

 this is especially the case with the achenium and caryopsis, which are hence popularly 

 called seeds. The corona of hairs which serves as an apparatus for the dissemination of 

 many seeds through the air is frequently developed in the caryopsis as an appendage of 

 the pericarp (as the pappus of Compositae, which properly replaces the superior calyx). 

 The wings answering the same purpose which are formed during the development of 

 the testa, of some seeds in dehiscent fruits (seen in an especially beautiful manner in 

 Bignonia) recur again on the pericarp of indehiscent fruits (as in Acer). The muci- 

 laginous epidermis spoken of above of the seeds of dehiscent fruits recurs in the epi- 

 dermis of the carcerulus of Sal-via and other Labiatae, &c. These and a number of 

 other facts show that all that is essentially required in the development both of the 



^ [For other recent attempts to classify fruits, see Dickson, Brit. Assoc. Rep. 1871, also Nature, 

 vol. IV, p. 347, and Journ. of Bot. 1871, p. 310; McNab, Nature, vol. IV. p. 475; Masters, 

 Nature, vol. V. p. 6 ; and Gray, Structural Botany.] 



