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loose spiral fibres (elaters), enclosed in membranous cases, among which sporules lie intermixed: when fully ripe, the membranous case usually disappears, the spiral fibres, which are powerfully hygrometric, uncurl, and the sporules are dispersed. When young, the conceptacle is enclosed in a membranous bag (epigonium), which it ruptures when it elongates, but which it does not carry upwards upon its point, as Mosses carry their calyptra. This part, nevertheless, bears the latter name.

Besides the conceptacles of Jungermannia, there are two other parts which are thought to be also intended for the purpose of reproduction : of these, one consists of spherical bodies, scattered over the surface of some parts of the frond, and containing a granular substance; the other is a hollow pouch, formed out of the two coats of a flat frond, and producing from its inside, which is the centre of the frond, numerous granulated round bodies which are discharged through the funnel-shaped apex of the pouch.

There are also other bodies situated in the axillæ of the perichætial leaves, called anthers (spermatocystidia, antheridia, pollinaria, staminidia), which “are externally composed of an extremely thin, pellucid, diaphanous membrane, within they are filled with a fluid, and mixed with a very minute granulated substance, generally of an olivaceous or greyish colour : this, when the anther has arrived at a state of maturity, escapes through an irregularly shaped opening, which bursts at the extremity.” Von Martius suspects these to be analogous to the sporangia of Azolla.

In Monoclea and Targionia organs nearly analogous to those of Jungermannia are formed for reproduction. In Targionia the antheridia are represented by M. Montagne as being embedded in disks very like the shields of Lichens. (Ann. Sc., n. s. ix. 100.)

In Marchantia the frond is a lobed flat green substance, not dividing into leaves and stems, but lying horizontally upon the ground, and emitting roots from its under surface. The organs of reproduction consist, firstly, of a stalked funguslike receptacle, carrying on its apex a calyptra, and bearing sporangia on its under side; secondly, of a stalked receptacle, plane on the upper surface, with oblong bodies embedded vertically in the disk, and called anthers; thirdly, “ of little open cups (cystula), sessile on the upper surface of the fronds, and containing minute green bodies (gemme), which have the power of producing new plants.” The first kind is usually considered a female flower, its spores being intermixed with elaters; the second male, and the third viviparous, apparatus. In the opinion of many modern botanists, the granules of both the first two are spores: about the function of the last there is no difference of opinion. Mirbel considers the first two to be male and female; but, whatever their functions may be, in structure there is but little analogy between them and the organs of more perfect plants. Meyen describes spermatic animalcules, resembling the genus Vibrio, as occupying the interior of each grain of the supposed pollen in Marchantia polymorpha. (Comptes Rendus, vi. 533.)

In Anthoceros, while the vegetation is the same as in Marchantia, the organs of reproduction are very different. They consist of a subulate column, issuing from a perichætium perpendicular to the frond, and dividing half way into two valves, which discover, upon opening, a subulate columella, to which sporules are attached without any elaters. There are also cystulæ upon the frond, in which are enclosed pedicellate reticulated bodies, called anthers.

Sphærocarpus consists of a delicate roundish frond, on the surface of which are clustered several cystulæ, each of which contains a transparent spherule filled with sporules.

In Riccia the spherules are not surrounded by cystulæ, but immersed in the substance of the frond.

7. Lichens.

These have a lobed frond or thallus (or blastema), the inner substance of which consists wholly of reproductive matter, that breaks through the upper surface in certain forms which have been called fructification. These forms are twofold; firstly, shields (scutella or apothecia), which are little coloured cups or lines with a hard disk, surrounded by a rim, and containing asci, or tubes filled with sporules; and,

secondly, soredia, which are heaps of pulverulent bodies scate tered over the surface of the thallus. The nomenclature of the parts of Lichens has been excessively extended beyond all necessity: it is, however, desirable that it should be understood by those who wish to read the systematic writers upon the subject. 1. Apothecia, are shields of any kind. 2. Perithecium, is the part in which the asci are immersed. 3. Hypothecium ; the substance that surrounds, or overlies the

perithecium, as in Cladonia. 4. Scutellum, is a shield with an elevated rim, formed by the

thallus. Orbilla, is the scutellum of Usnea. 5. Pelta, is a flat shield without any elevated rim, as in the

genus Peltidea. 6. Tuberculum, or Cephalodium, is a convex shield without an

elevated rim. 7. Trica, or Gyroma, is a shield, the surface of which is

covered with sinuous concentric furrows. 8. Lirella, is a linear shield, such as is found in Opegrapha,

with a channel along its middle. 9. Patellula ; an orbicular sessile shield, surrounded by a rim

which is part of itself, and not a production of the thal

lus, as in Lecidea. D. C. 10. Globulus ; a round deciduous shield, formed of the thallus,

and leaving a hollow when it falls off, as in Isidium. D. C. 11. Pilidium ; an orbicular hemispherical shield, the outside of

which changes to powder, as in Calycium. D.C. 12. Podetia ; the stalk-like elongations of the thallus, which

support the fructification in Cenomyce. 13. Scypha (oplarium, Neck.), is a cup-like dilatation of the

podetium, bearing shields on its margin. 14. Soredia (globuli, glomeruli), are heaps of powdery bodies

lying upon any part of the surface of the thallus. The bodies of which the soredia are composed are called

conidia by Link, and propagula by others. 15. Cystula, or Cistella ; a round closed apothecium, filled with

sporules, adhering to filaments which are arranged like

rays around a common centre, as in Sphærophoron. 16. Pulvinuli, are spongy excrescence-like bodies, sometimes

C

rising from the thallus, and often resembling minute

trees, as in Parmelia glomulifera. Greville. 17. Cyphelle, are pale tubercle-like spots on the under surface

of the thallus, as in Sticta. Grev. 18. Lacune, are small hollows or pits on the upper surface of

the thallus. Grev. 19. Nucleus proligerus, is a distinct cartilaginous body, coming

out entire from the apothecia, and containing the spo

rules. Grev. 20. Lamina proligera, is a distinct body containing the spo

rules, separating from the apothecia, often very convex and variable in form, and mostly dissolving into a gela

tinous mass. Grev. 21. Fibrilla, are the roots, 22. Excipulus, is that part of the thallus which forms a rim

and base to the shields. 23. Nucleus, is the disk of the shield which contains the spo

rules and their cases. 24. Asci, are tubes, in which the sporules are contained while

in the nucleus. 25. Thallodes, is an adjective used to express an origin from

the thallus: thus, margo thallodes signifies a rim formed by the thallus, excipulus thallodes a cup formed by the

thallus. 26. Lorulum, is used by Acharius to express a filamentous

branched thallus. 27. Crusta, is a brittle crustaceous thallus. 28. Gongyli, are the granules contained in the shields, and

have been thought to be the spores by which Lichens are propagated: but this is doubted by Agardh.

8. Algacea. These, with Fungi, constitute the lowest order of vegetable developement: they vary from mere microscopic objects to a large size, and are composed of cellular tissue in various degrees of combination; some are even apparently animated, and thus form a link between the two great kingdoms of organised matter. Their spores are either scattered

through the general mass of each plant, or collected in certain places which are more swollen than the rest of the stem, and sometimes resemble the pericarpia of perfect plants.

Nothing which can be compared to male organs has yet been found in Algaceæ; but it is not impossible that matter, possessing the properties of pollen, may be mixed up with the spores, in the inside of the tubes or other bodies in which they are developed. The mode of propagation in Algaceæ is extremely variable, but apparently always takes place by the formation of spores, either within the ordinary cells of the plant, or within sporangia of one kind or other. The Zygnemata have the curious attribute of forming their spores by the copulation of two contiguous branches.

The terms used in speaking of the parts of these plants are the following :1. Gongylus; a round hard body, which falls off the mother

plant, and produces a new individual: this is found in

Fuci. W. 2. Thallus ; the plant itself. 3. Apothecia ; the cases in which the organs of reproduction

are contained. 4. Peridiolum, Fr.; the membrane by which the sporules are

immediately covered. 5. Granula ; large sporules, contained in the centre of many

Algaceæ; as in Gloionema of Greville. Crypt. Fl. 6. 30. 6. Pseudoperithecium ;) terms used by Fries to express such 7. Pseudohymenium; } coverings of sporidia as resemble 8. Pseudoperidium; J in figure the parts named peri

thecium, hymenium, and peridium in other plants: see

those terms. 9. Sporidia ; granules which resemble sporules, but which

are of a doubtful nature. It is in this sense that Fries declares that he uses the word : vide Plant. homonom.

p. 294. They are also called Spora. 10. Phycomater, Fries; the gelatine in which the sporules of

Byssaceæ first vegetate. 11. Vesiculæ ; inflations of the thallus, filled with air, by

means of which the plants are enabled to float.

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