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males and the larger females; which has been supposed to be proved by the experiments of M. Savi of Pisa. This observer introduced into different vessels, 1. the granules; 2. the grains; and, 3. the two intermixed. In the two first nothing germinated; in the third the grains floated to the surface and developed themselves perfectly. These observations have, however, been repeated by M. Duvernoy without the same result. And it must be remarked that, if the functions of these grains and granules be what has been attributed to them, the male power of action and the female powers of reception cannot exist till both are discharged from the membranes or involucra, in which they are contained and placed in contact in water. Is it impossible that the granules or supposed male organs should be only grains in an imperfectly developed condition?

5. Mosses.

In the structure of these plants neither vessels nor woody fibre are employed; and from henceforward those organs disappear from the organisation of all the tribes to be noticed. Their stem consists of elongated cellular tissue, from which arise leaves composed, in like manner, entirely of cellular tissue without woody fibre; the nerves, as they are called, or, more properly speaking, costa, which are found in many species, being formed by the approximation of cellules more elongated than those that constitute the principal part of the leaf. The leaves are usually a simple lamina; but in Polytrichum and a few others they are furnished with little plates, called lamellæ, running parallel with the leaf, and originating from the upper surface. At the summit of some of the branches of many species are seated certain organs, which are called male flowers, but the true nature of which is not understood. They are possibly organs of reproduction of a particular kind, as both Mees and Haller are recorded to have seen them produce young plants.

Agardh says they have only the form of male organs; and that they really appear to be gemmulæ. By Hedwig they were called spermatocystidia.

But, whatever may be the nature of these organs, there is

no doubt of the reproductive functions of the contents of what is named the theca or capsule, which is a hollow urn-like body, containing sporules: it is usually elevated on a stalk, named the seta, with a bulbous base, surrounded by leaves of a different form from the rest, and distinguished by the name of perichatial leaves. If this theca be examined in its youngest state, it will be seen to form one of several small sessile ovate bodies (pistillidia, Agardh; prosphyses, Ehrhart; adductores, Hedwig), enveloped in a membrane tapering upwards into a point; when abortive they are called paraphyses. In process of time the most central of these bodies swells, and bursts its membranous covering, of which the greatest part is carried upwards on its point, while the seta on which the theca is supported lengthens. This part, so carried upwards, is named the calyptra: if it is torn away equally from its base, so as to hang regularly over the theca, it is said to be mitriform, but if it is ruptured on one side by the expansion of the theca, which is more frequently the case, it is denominated dimidiate. When the calyptra has fallen off or is removed, the theca is seen to be closed by a lid terminating in a beak or rostrum: this lid is the operculum, and is either deciduous or persistent. If the interior of the theca be now investigated, it will be found that the centre is occupied by an axis, called the columella; and that the space between the columella and the sides of the theca is filled with sporules. The brim of the theca is furnished with an elastic external ring, or annulus, and an interior apparatus, called the peristomium: this is formed of two distinct membranes, one of which originates in the outer coating of the theca, the other in the inner coat; hence they are named the outer and inner peristomia. The nature of the peristomium is practically determined at the period of the maturity of the theca. At this time both membranes are occasionally obliterated; but this is an unfrequent occurrence: sometimes one membrane only remains, either divided into divisions, called teeth, which are always some multiple of four, varying from that number as high as eighty, or stretching across the orifice of the theca, which is closed up by it; this is sometimes named the tympanum. Most frequently both membranes are present, divided into teeth, from

differences in the number or cohesion of which the generic characters of mosses are in a great measure formed. For further information upon the peristomium I must refer to Mr. Brown's remarks upon Lyellia, in the 12th volume of the Linnean Transactions.

The interior of the theca is commonly unilocular; but in some species, especially of Polytrichum, it is separated into several cells by dissepiments originating with the columella.

If at the base of the theca there is a dilatation or swelling on one side, this is called a struma; if it is regularly lengthened downwards, as in most of the Splachnums, such an elongation is called an apophysis.

The only material exception to this description of Musci exists in Andræa, in which the theca is not an urn-like case, but splits into four valves, cohering by the operculum and base. From the foregoing description, it will be apparent that the organs of reproduction of mosses cannot be said to be analogous to the parts of fertilisation of perfect plants. I must not, however, omit the opinion of other botanists upon this subject. The office of males has been supposed by Micheli to be performed by the paraphyses; by Linnæus and Dillenius, by the thecæ; by Palisot de Beauvois, by the sporules; by Hill, by the peristomium; by Koelreuter, by the calyptra; by Gærtner, by the operculum; and, finally, Hedwig has supposed the males to be the staminidia. The female organs were thought by Dillenius and Linnæus to be assemblages of staminidia; by Micheli and Hedwig, the young thecæ; and, by Palisot de Beauvois, the columella.

For some suggestions as to the analogy that is borne between the organs of mosses and of other plants, see MORPHOLOGY hereafter.

6. Hepatica.

These differ remarkably from each other in the modifications of their organs of reproduction, while they have a striking resemblance in their vegetation. This latter, which bears the name of frond or thallus, is either a leafy branched tuft, as in mosses, with the cellular tissue particularly large, and the leaves frequently furnished with lobes, and appendages

at the base, called stipulæ or amphigastria; or a sinuous flat mass of green vegetable matter lying upon the ground.

In Jungermannia, that part which is most obviously connected with the reproduction of the plant, and which bears an indisputable analogy to the theca of mosses, is a valvular brown case, called the capsule or conceptacle, elevated upon a white cellular tender seta, and originating from a hollow sheath or perichætium arising among the leaves. This conceptacle contains a number of spiral loose fibres (elateres), 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, 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, (or spermatocystidia, by Hedwig, and staminidia, by Agardh,) 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."

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In Monoclea and Targionia organs very analogous to those of Jungermannia are formed for reproduction.

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 fungilliform receptacle, carrying on its apex a calyptra, and bearing thecæ on its under side; secondly, of a stalked receptacle, plane on the upper surface, with oblong bodies imbedded 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 (gemma), which have the power of producing new plants." The first kind is usually considered a female flower, its sporules intermixed with elateres : the second male, and the third viviparous apparatus. In the opinion of many modern botanists, the granules of both the two first are sporules: about the function of the last there is no difference of opinion.

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 opening halfway into two valves, which discover, upon opening, a subulate columella, to which sporules are attached without any elateres. 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. Lichenes.

These have a lobed frond or thallus, the inner substance of which consists wholly of reproductive matter, which breaks through the upper surface in certain forms, which have been called fructification. These forms are twofold; firstly, shields, or scutella, 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 scattered over the surface of the thallus. The nomenclature of the parts of lichens has been excessively extended beyond all necessity: it is, however,

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