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 N. 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^er, 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 cf long hairs is developed, as in Jlsclepias syriaca. The epidermal 
cells of some seeds, as the Flax, 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 Compositse, 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 Labiatse, &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, aliO 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 Gx^y, Structural Botany.] 
