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perfect feeds, is the more probable, as thefe bulbs in the alas of the leaves are found only in fome of the hypna, and others of a few other genera, whereas the propagation is as quick and certain in thofe which have none of them, as in thofe which have j and the want of female parts of fructification, which makes fo many defiderata in the Linmesn fyftcm of botany, is eafily made up, and the whole explained according to the nfual courfe of nature in other vegetables, by allowing the powder in the capfules to be real feeds, and the fmall glo- bules on the pointals furrounding the aperture of the capfule, the farina.
The opinion of the Moffes growing only from thefe nodules in the al« of the leaves, or from the impregnated ends of the branches which had received the powder from the capfules, was originally founded on the obferving, that the trailing or branched hypnums annually grew out into length, from the ■ extremities of all their branches, and annually loll as much of the old ftaik at the root, as they gained of the new at the fum- mit ; but it appears from further obfervations, that they are real feeds which are contained in form of powder in the cap- fules; fince the bryums, and many others, are found grow- ing from fmall points or fpots, which are afTemblagcs of their minute leaves, propagated on the ground, under the old ones juft where the powder of the capfules has fallen ; and tho' it be allowed, that the hypnums and other trailing Moffes do grow from the ends of the branches, yet they may alfo be produced in form of new plants, from regular and perfect feeds fhed from the capfules. It is certain that the bryums are by this means propagated and fpread into large tufts, and the other genera may alfo be fo propagated, tho' they have befide a property of encreafing by growth of the ftaik ; which feerns no other than the property of many of the larger plants to creep at the root, and fhoot out in length greatly from the extremities of their horizontal branches, lying on or under the ground, as thofe fpreading parts may more properly be fo cal- led than roots, the fibres pufhed out from them perpendicu- larly into the earth, being properly the roots ; and it is well known that thefe plants, tho' they propagate themfelves thus hy the root, produce feeds alfo like the others, by which they may be equally propagated ; and this analogy is to be carried yet farther j for as thofe plants which creep by the roots, pro- duce fewer feeds than thofe which are propagated only by feeds, fo the hypnums, which are the genus of Moffes in which this growth by the ftalk is principally obferved, are very thinly befet with capfules of ked, and many of them produce but very few in a feafon ; whereas the brya, and other Moffes, which have not this advantage of growing from the ends of the ftalks, are found every year profufely covered with capfules from every tuft ; nay, there is fcarce any branch which does not produce its capfule. Now if thefe capfules contained only a farina capable of impregnating the nodules, or the ends of the branches, it is obvious there would be as much of it required for the hypna as for any other kinds of Moffes ; but if they are real and perfect feeds, it is no wonder that nature has given them profufely, to fuch kinds as are to be propagated only by feeds, and more fparingly to thofe which are propagated alfo by the increafe of the branches. To this it may finally be added, that the ferns and other epi- phyllofpermous plants approach moft of all others to the nature of the Moffes ; and tho' it has been fufpected by many, that the fine powder at the back of their leaves was not feeds, but only a farina ; yet it is now well known that it is true and perfect feed, Fince, under many fpecies of them, there are conftantly found new and felf-fown plants arifing in their nrft rudiments of leaves and figure, which have plainly grown from the duft or powder fallen from the old plants; and as this is now found to be the cafe in regard to the ferns, proba- bly it will alfo appear the fame in regard to the Moffes, when they have been yet farther examined than at prefent. But whether thefe grains of powder have the lobes and radicle by which the feeds of larger plants propagate themfelves, or whe- ther they grow into plants like the parent ones, in the manner of the lichens, by mere expanfion, is a thing that requires farther observations to determine.
Some of the Moffes, it is evident, approach to the nature of the plant*, which have their male and female parts in the fame flower, and to thofe which have them in different ones. The lichens have their leaves notched and jagged like thofe of the perfea plants, and have, in the fame manner, their under furtace different from the upper. Thefe have their male flowers or heads on long pedicles; thefe heads contain only farina, and the feeds are lodged in little cups or dimes on the furface of the leaves. The next in perfection to thefe are the lycopo- dioides, which have flowers with tarina, and fruits with feeds, difpoled along the fame fpike. The mnia have heads of two Kinds, the one membranaceous, like thofe of the hypnums and other Moffes, and the other dufty, and containing a pow- der whole on their furface; the one of thefe plainly contains the farina- the other the feed. The lichenaftra are very fel- dom found with feeds on them ; but they creep greatly by the roots j whence a new propagation by feeds is lefs neceffary. 1 he polymelia are fuppofed to carry onlv a farina in their Heads, and their branches foliated at the 'ends, to carry the
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feeds which are to be impregnated. This has been thecom- mon opinion ; but it wants confirmation. Some of the bryums have the fame appearance of a female part, and the young no- dules in the alse of the leaves of the hypnums are generally alfo referred to the fame ufe. But thefe are conjectures j and the much more probable opinion is, that the powder in the heads of all the Moffes is true feed, which in general is im- pregnated with farina from the pointals, over the mouth of the capfule ; and in fome instances, as in the mnia, &c. as in fome of the more perfect plants, from different flowers in a different part of the plant. Dillen. Hift. Mufc, Introit. The manner of feeding of M&ffes in general may be in fome degree gueffed at by that of one genus of them, which has been traced through all its ltages, and to which moft of the others, though every genus has its diftinct frucliftcation in fome refpects, yet bear a very great general analogy. The genus already obferved, is that called by Dr. Dillenius, the hypnum. The fpecies of this are very numerous and com- mon ; but that particular one which was the fubject of thefe obfervations, is the fhort-branched filky kind, common on old walls ; and called by that author in his hiftory, Hypnum vulgare, ferv'tcum, recurman, capjidis ereiiis cufpidatis. The head of this Mofs appears to the naked eye a fmall fmooth brownifh yellow oblong body, of about a ninth of an inch long; this is covered at Its upper end with a membranaceous calyptra or hood, in fhape refembling an extinguifher, or a funnel inverted. When this calyptra is taken off, and the head viewed with a microfcope, the furface of it is feen to be ridged with longitudinal ftria;. The bafis of the head is of a deep orange colour, and more opake than the reft ; and the top is bounded by an orange-coloured ring fwelling out fome- thing beyond the furface of the contiguous parts of the head. Good glafles fhew that in this head there are not wanting the parts elTential to the fructification of what are ufually called the more perfect plants. This ring is truly a monophyllous undulated calyx, within which arife fixteen pyramidal fim- briated ifamina ; thefe are of a pale greenifh colour, and are loaded with a whitifh oval farina. The ftamina all bend to- ward each other from' their bafes, and almoft meet in a point at their tops. This is their appearance when the head is nearly ripe ; and immediately under the arch formed by thefe ftami- na, is a cylindric hollow piftillum, through which the farina makes its way, and is difperfed among the feeds in the head. The fruit is a large capfule, filling every part of the membrane which Clews' itfelf on the outfide of the head, and in moft places is contiguous to it. This capfule is filled with perfect and very beautiful feeds ; they are round, tranfparent when unripe, but afterwards opake, and of a very beautiful green, which colour they retain even when dried. Philof. Tranf. No. 478. Sect. 12.
When this head is firft produced from the plant, the ftamina are very flender, and ftand erect ; the head is fcarce any thicker than the ftalk, and the calyptra covers it all over r to fhield the tender fubftance of the farina from external injuries. As the farina afterwards f wells in the ftamina, the feeds in the head increafe alfo in bulk, and by their increafe the head is more extended in thicknefs, and the ftamina are by this means feparated farther and farther from each other a; their bafes, but bend inwards toward their points, fo as to form a kind of arched covering over the ftigma of the piftillum which is An- gle ; and from hence the farina falls as it ripens into the head, and impregnates the feeds. Id. Ibid.
All the Moffes, liverworts, and the other plants of the fame character, poffefs the fame general virtues of drying and aftrin- gency. Moss on Trees, in gardening. The growth of large quanti- ties of Mofs on any kind of tree is a diftemper of very bad confequence to its increafe, and much damages the fruit of the trees of our orchards.
The prefent remedy is the fcraping it off from the body and large branches, by means of a kind of wooden knife, that will not hurt the bark, or with a piece of rough hair cloth, which does very well after a foaking rain. But the moft ef- ' fectual cure, is the taking away the caufe. This is to be done hy draining off all the fuperfluous moifture from about the roots of the trees, and may greatly be guarded againft in the firft planting of the trees, by not letting them too deep. If trees ftand too thick in a cold ground, they will always be covered with Mofs ; and the beft way to remedy the fault, is to thin them. When the young branches of trees are covered with a long and fhaggy Mofs, it will utterly ruin them ; and there is no way to prevent it, but to cut off the branches near the trunk, and even to take off the head of the tree, if necef- fary"; for it will fprout again ; and if the caufe be in the mean time removed by thinning the plantation, or draining the land, the young fhoots will continue clear after this. If the trees are covered with Mofs, in confequence of the grounds being too dry, as this will happen from either ex- treme in the foil, then the proper remedy is the laying mud from the bottom of a pond or river, pretty thick about the root, opening the ground to fome diltance and depth to let it in ; this will not only cool it, and prevent its giving growth to any great quantity of Mofs, but it will alfo prevent the
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