the seed, the latter being contained within the former. When the ovary is inferior, or coheres with the calyx, the latter and the pericarp are usually so completely united as to be inseparable and undistinguishable: in such cases it is usual to speak of the pericarp without reference to the calyx, as if no such union had taken place. Botanists call a fruit, the pericarp of which adheres to the calyx, an inferior fruit (fructus inferus); and that which does not adhere to the calyx, a superior fruit (fructus superus). But Desvaux has coined other words to express these ideas: a superior fruit he calls. autocarpien; an inferior fruit, heterocarpien; terms unnecessary and unworthy of adoption.

Every thing which in a ripe fruit is on the outside of the real integuments of the seed, except the aril, belongs to the pericarp. It consists of three different parts, the epicarp, the sarcocarp, and the endocarp; terms contrived by Richard, and useful in practice.

The epicarp is the external integument or skin; the endocarp, called putamen by Gærtner, the inner coat or shell; and the sarcocarp, the intermediate flesh. Thus, in the peach, the separable skin is the epicarp, the pulpy flesh the sarcocarp, and the stone the endocarp or putamen. In the apple and pear the epicarp is formed by the cuticle of the calyx, and the sarcocarp is confluent with the remainder of the calyx in one fleshy body.

The pericarp is extremely diversified in size and texture, varying from the dimension of a single line in length to the magnitude of two feet in diameter; and from the texture of a delicate membrane to the coarse fabric of wood itself, through various cartilaginous, coriaceous, bony, spongy, succulent, or fibrous gradations.

The base of the pericarp is the part where it unites with the peduncle; its apex is where the style was: hence the organic and apparent apices of the fruit are often very different, especially in such as have the style growing from their sides, as in Rosacea and Chrysobalanaceæ, Labiata and Boraginaceæ.

When a fruit has arrived at maturity, its pericarp either continues perfectly closed, when it is indehiscent, as in the

hazel nut; or separates regularly round its axis, either wholly or partially, into several pieces: the separation is called dehiscence, and such pieces valves; and the axis from which the valves separate, in those cases where there is a distinct axis, is called the columella.

When the dehiscence takes place through the dissepiments, it is said to be septicidal; when through the back of the cells, it is called loculicidal; if along the inner edge of a simple fruit it is called sutural; if the dissepiments are separated from the valves, the dehiscence is named septifragal.

In septicidal dehiscence the dissepiments divide into two plates and form the sides of each valve, as in Rhododendron, Menziesia, &c. Formerly botanists said that in this sort of dehiscence the valves were alternate with the dissepiments, or that the valves had their margins turned inwards.

This may

d

169

d

α

d

v

be understood from fig. 169., which represents the relative position of parts in a transverse section of a fruit with septicidal dehiscence; v being the valves, d the dissepiments, and a the axis.

In loculicidal dehiscence the dissepiments form the middle of each valve, as in the lilac, or in the diagram 170., where the letters have the same value as above. In this it was formerly said that the dissepiments were opposite the valves.

In septifragal dehiscence the dissepiments adhere to the axis and separate from the valves, as in Convolvulus; or in the diagram 171., lettered as before.

In sutural dehiscence there are no dissepiments, the fruit being composed of only one carpel, as the Pea.

d

a

d

170

171

Besides these regular forms of valvular dehiscence, there is a mode which obtains in a very few plants, called circumscissile. This occurs by a transverse circular separation, as in Anagallis; in Jeffersonia it only takes place half round the fruit.

Valvular dehiscence, which is by far the most common mode by which pericarps open, must not be confounded with either rupturing or solubility,-irregular and unusual contrivances of nature for facilitating the dispersion of seeds. In valvular dehiscence the openings have a certain reference to the cells, as has been already shown; but neither rupturing nor solubility bear any distinct relation to the cells. Rupturing consists in a spontaneous contraction of a portion of the pericarp, by which its texture is broken through, and holes formed, as in Antirrhinum and Campanula. Solubility arises from the presence of certain transverse contractions of a one-celled pericarp, through which it finally separates into several closed portions, as in Ornithopus.

For the nature of the placenta and umbilical cord see the observations under ovary. These parts, which are mere modifications of each other, essentially appertain to the pericarp, in which the former often acquires a spongy dilated substance, occasionally dividing the cells by spurious dissepiments, and often giving to the fruit an appearance much at variance with its true nature. In some seeds, as Euonymus europæus, it becomes exceedingly dilated around each seed, forming an additional envelope, called aril. The true character of this organ was unknown till it was settled by Richard: before his time the term was applied, not only in its true sense to an enlargement of the placenta, but also to the endocarp of certain Rubiacea and Rutaceæ, to the seed-coat of Jasminum, Orchidea, and others, and even to the perianth of Carex. A very remarkable instance of the aril is to be found in the nutmeg, in which it forms the part called the mace surrounding the seed. It is never developed until after the fertilisation of the ovule.

Having thus explained the structure of the pericarp, it is in the next place necessary to enquire into the nature of its modifications, which in systematic botany are of considerable importance. It is, on the one hand, very much to be regretted that the terms employed in this department of the science, which is that of Carpology, have been often used so vaguely as to have no exact meaning; while, on the other hand, they have been so exceedingly multiplied by various writers, that

the language of carpology is a mere chaos. In practice but a small number of terms is actually employed; but it cannot be doubted that, if it were not for the inconvenience of overburdening the science with words, it would conduce very much to clearness of description if botanists would agree to make use of some very precise and uniform nomenclature.

What, for instance, can be more embarrassing than to find the term nut applied to the superior plurilocular pericarp of Verbena, the gland of Corylus, and the achenia of Rosa and Borago; and that of berry to the fleshy envelope of Taxus, the polyspermous inferior fruit of Ribes, the succulent calyx of Blitum, and several other things?

So much discordance, indeed, exists in the application of terms expressive of the modifications of fruit, that it is quite indispensable to give the definitions of some of the most eminent writers upon the subject in their own words, in order that the meaning attached by those authors to carpological terms, when employed by themselves, may be clearly understood.

In the phraseology of writers antecedent to Linnæus, the following are the only terms of this description employed; viz.1. Bacca, a berry: any fleshy fruit.

2. Acinus, a bunch of fleshy fruit: especially a bunch of grapes.

3. Cachrys, a cone: as of the pine tree.

4. Pilula, a cone like the Galbulus of modern botanists.

5. Folliculus (Fuchs), any kind of capsule.

6. Grossus, the fruit of the fig unripe.

7. Siliqua, the coating of any fruit.

In his Philosophia Botanica, LINNEUS gives the following definitions of the terms he employs :

1. Capsula, hollow, and dehiscing in a determinate manner. 2. Siliqua, two-valved, with the seeds attached to both

sutures.

3. Legumen, two-valved, with the seeds attached to one suture only.

4. Conceptaculum, one-valved, opening longitudinally on one side, and distinct from the seeds.

5. Drupa, fleshy, without valves, containing a nut. 6. Pomum, fleshy, without valves, containing a capsule. 7. Bacca, fleshy, without valves, containing naked seeds. 8. Strobilus, an amentum converted into a pericarp. GÆRTNER has the following, with definitions annexed to them:

1. Capsula, a dry, membranous, coriaceous, or woody pericarp, sometimes valveless, but more commonly dehiscing with valves. Its varieties are,

a. Utriculus, a unilocular one-seeded capsule, very thin and transparent, and constantly valvular; as in Chenopodium, Atriplex, Adonis.

b. Samara, an indehiscent, winged, one- or two-celled capsule; as Ulmus, Acer, Liriodendron.

c. Folliculus, a double one-celled, one-valved, membranous, coriaceous capsule, dehiscing on the inside, and either bearing the seed on each margin of its suture, or on a receptacle common to both margins; as Asclepias, Cinchona, and Vinca.

2. Nux, a hard pericarp, either indehiscent or never dividing into more than two valves; as in Nelumbium, Boragineæ, and Anacardium.

3. Coccum, a pericarp of dry elastic pieces or coccules, as in Diosma, Dictamnus, Euphorbia.

4. Drupa, an indehiscent pericarp with a variable rind, very different in substance from the putamen, which is bony, as in Lantana, Cocos, Sparganium, Gaura, &c.

5. Bacca, any soft pericarp, whether succulent or otherwise; provided it does not dehisce into regular valves, nor contain a single stone adhering to it. Of this the following are kinds :

a. Acinus, a soft, succulent, semi-transparent, unilocular

berry, with one or two hard seeds; as the Grape, Rivina, Rhipsalis, Rubus, Grossularia, &c.

b. Pomum, a succulent or fleshy, two- or many-celled berry, the dissepiments of which are fleshy or bony, and coherent at the axis; as Pyrus, Crataegus, Cydonia, Sapota, and others.