THE STUDY OF MOSSES.*

THE most obtuse observer cannot wander through the country without admiring the beauty of mosses. In many places they carpet the ground with a rich living pile of pleasant green, in others they clothe the rocks, form a vesture for the tree-trunk, enrich the parti-coloured thatch on the quaint old cottage, or sedulously haunt the crevice of the wall. In a technological sense they are not of much use, except in the condition of peat; perhaps simply because man is not yet sufficiently instructed to know what to do with them: but in the world of nature they play an important part, making their appearance at times and under circumstances when higher forms of vegetation would not grow. Thousands and millions are the tons of mineral and aeriform matter which they transmute every season into their delicate tissues; and when these decay, they produce no inconsiderable amount of vegetable soil. They likewise form the home and shelter for numerous minute insects, even for rotifers; and they tell their story of the wonderful ways of life and organization not less strikingly than the widest spreading, or the loftiest soaring, of the stateliest families of trees. Like all low, or comparatively lowly members of the organic world, they contribute most importantly to our knowledge of the laws, processes, and structures that distinguish living beings. We cannot assert that they constitute a page of nature's primer, and furnish elementary lessons in A, B, C, for her human pupils to study; as little was known, or could be known of them, or of objects standing upon a similar or lower grade of structural rank, until science had been considerably advanced, and instruments like the microscope had been fabricated to assist in the delicate and complicated labours of research. The simplest form of life is not after all simple in any ordinary sense of the word. We talk of "unicellular plants and animals," but Professor Karstent tells us this is erroneous, "owing to the complicated structure of the tissue cells which enter into the composition of developed organisms ;" and if we mastered the structure of the cell, we should still be puzzled to account for the functions which it performs, some of which we know to be physical, while we call others "vital," without attaching any precise or definite meaning to the term.

Still, though nature's secrets lie always deep, we are

Handbook of British Mosses, comprising all that are known to be Natives of the British Isles. By the Rev. M. J. Berkeley, M.A., F.L.S., author of "Introduction to Cryptogamic Botany," ""Outlines of British Fungology," etc.

Lovell Reeve & Co.

+ See Annals of Natural History, No. 67.

materially assisted in unravelling them by the examination of objects that present fewest complications; and hence, among others, mosses are very useful to the scientific botanist, as they are sure from their beauty to interest the more casual observer. Unfortunately, they do not readily admit of any classification which is natural and intelligible. In the Micrographic Dictionary, which has a high reputation for its botanical articles, the system of Müller is followed, while Mr. Berkeley considers that the arrangement of Dr. Montagne in D'Orbigny's Dictionary is the most convenient as regards the natural orders, and he tells us he has adopted it with few exceptions. He arranges the mosses under four orders-Pleurocarpi, with the fruit lateral and springing immediately from the stem; Acrocarpi, with the fruit terminal; Schistocarpi, with the fruit splitting longitudinally into four or more valves, adhering above; and Syncladei, mosses with fasciculate branches. The artificial group, Cladocarpi, with terminal fruit on short lateral branches, he judiciously arranges under other heads, on the ground that "it is not strictly natural, and the character is difficult of application, as Acrocarpus and Cladocarpus species occur in the same genus."

The shape of the spore vessel or capsule, the form of the hood, the presence or absence of the peristome, and its exquisite rows of finely-coloured teeth, the shape of the cells forming the leaf tissue, and the mode of branching-these are the chief points to be attended to in the examination of mosses; but it is to be regretted that as yet no sufficiently dominating characters have been discovered to enable those who have devoted themselves to the inquiry to establish genera which are at once intelligible, and correspond with natural conditions.

Mr. Berkeley, who is no mean authority on these subjects, after devoting, as his present work proves, much attention to the question, tells us that "on the whole, the state of Bryology must be considered as extremely imperfect," and he adds, "the entire subject clearly wants the revision of some master mind."

The reproductive processes in mosses are very curious and characteristic. As is common with plants, and with many animals, they have two or more modes of multiplication-the one a genuine sexual process, the others belonging to the category of budding. In the elegant urns, which form such beautiful objects for the microscope, the moss produces spores; but the result of their germination differs materially from that of the spores of ferns. Mr. Berkeley thus comments upon this subject:-"In ferns and their allies, the result of germination is the production of a cellular expansion of various forms, whether globose, or scale-like, or irregular, whether more or less differen

tiated and distinct from the spore itself, or confluent with it externally or internally, or both, on which, or within the substance of which, at least in the more normal cases, two organs are produced of different sexes, the one of which, called an archegonium," consists of a pitcher-shaped cyst, within which there is a free single cell at the base, which is destined, after impregnation, to produce first an embryo, and then, by continued development, a perfect plant like the parent. In mosses, on the contrary, and their allies, the object, after germination, is to form a more or less filamentous, or scale-like stratum, resembling either a little green lichen, or one of the verdant thread-like confervæ, such as Lyngbya muralis, which clothes damp trees or the soil at the base of walls on the northern side, or that which is least exposed to the direct rays of the sun; and when this is perfected, nodules appear, which by cell formation give rise to the proper plant, whether symmetrical or unsymmetrical, whose office is to produce fruit. On this plant, then, either in the same or in distinct individuals, male and female organs are produced, resembling more or less closely the antheridia and archegonia of ferns. In the latter there is a cell at the base analogous to that in the archegonia of ferns, which is destined to be fertilized by spermatozoids formed in the tissue of the antheridia." The result of the fertilization is, however, distinct from that of ferns, for in their case germination produced a prothallus and impregnation afforded a true plant, "whereas in mosses and moss allies the cell division of the basal cell of the archegon* is a sporangium, or, as it is frequently called, a capsule or theca, which, with various modifications, gives rise to spores."

Warmth and moisture cause moss spores to burst their outer membranes, when the inner one puts forth an elongation which forms a green thread, and from these threads fertile buds arise. The behaviour of these threads has attracted the attention of Dr. Hicks, but Mr. Berkeley does not accept that gentleman's conclusions. He says:" "Dr. Hicks, in the 23rd vol. of the Transactions of the Linnean Society has described wonderful changes which take place in these threads, and their conversion into several genera of algae, besides the formation of zoospores; but as he does not identify the species to which he observed the threads belonged, and the production of zoospores is a circumstance so extremely anomalous, we find it difficult to believe that he had really portions of some moss before him, and not the threads of algae accidentally intermixed."

Many mosses are readily cultivated, and afford elegant "adornments" for what our friend Shirley Hibberd calls

The archegon is the rudimentary organ which represents the ovule in the higher flowerless plants.

"Homes of Taste." Mr. Stark gives a long list of these, amongst which are species of Hypnum, Orthoslichum, Polytrichum, Trichostomum, Andrea, Bryum, etc., etc. Of course the natural habits of the mosses must be considered, some liking a large allowance of moisture, and others preferring a situation that is dry.

We do not think it is any argument against a system of classification based on minute structure, that the determination of genera or species requires the aid of the microscope, as, thanks to the competition amongst excellent makers, instruments sufficient to follow the researches of others can be obtained for very moderate prices, and nine-tenths of the pleasure which the moss tribe, or any other small plants whose parts are minute, are able to afford to their admirers, must be obtained through the medium of considerable magnification. On this ground we confess to have some leaning towards the system of Müller, but every arrangement in the present state of the science must be regarded as provisional, and the consolation for those who have to take the trouble of getting up an elaborate nomenclature, to find it replaced a few years hence by another, must be found in the fact that they cannot study mosses upon any system without obtaining a large amount of positive information, which must remain valuable, whatever additions may be made to the store, or whether other genera are destined to suffer the fate of Gymnostomum, and find themselves properly distributed amongst widely distant groups.

In Mr. Berkeley's work the student will find the inestimable advantage of several hundreds of beautifully-executed coloured figures of native plants, and of their most important parts. By these he will be materially assisted in the determination of species, and also instructed what to see with the microscope in the arrangement and form of cells, the character of the spore vessel, the peristome, etc., etc. It is also proper to state that although Mr. Berkeley modestly disclaims originality, he has personally examined the objects described, and written his account of them with the especial purpose of assisting the collector of British specimens. The work is handsomely printed, and the coloured illustrations of unusual merit.

THE SOURCES OF THE NILE.

BY PROFESSOR D. T. ANSTED, M.A., F.R.S., ETC.

IN our number for June appeared a brief notice of a few words, announcing the intelligence that Captain Speke had succeeded in identifying the African lake, VICTORIA NYANZA, before visited by him, south of the equator, with the great father of waters, old NILUS; thus solving a very important section of one of the most important of all geographical problems, and obtaining for England and the nineteenth century a reputation for discovery that the wisest of the ancient Egyptians and their conquerors from the earliest days of civilization have failed to

secure.

Since those few lines were written Captain Speke and his fellow-traveller, Captain Grant, have returned to England, and have communicated some of the main results of their long, arduous, and dangerous expedition. Before giving an outline of these, let us briefly review the previous state of the problem and the extent of the work really done. Besides being of the highest interest as a question of descriptive geography, the results of exploration in north-eastern Africa, as commenced by Captain Burton and Captain Speke, and now continued and nearly completed by the latter, are of the most extraordinary interest, and help us to understand the physical geography and resources of a large section of the African continent. key to the explanation of all that is peculiar to Africa has been now obtained by the combined labours of Livingstone, Burton, Speke, Grant, and Petherick.

The

It was towards the end of June, 1857, that Captain Burton and several companions left the African coast near Zanzibar, on their way into the interior, determined to attempt the discovery of the sources of the White Nile from the east and south, instead of repeating the attempts that had been so frequently and unsuccessfully made to trace the river by following it up

stream.

From the time of Herodotus downwards there had been vain attempts made by European explorers to discover where the waters of the great river originated, and what was the cause of that mysterious rise by which Egypt was flooded and fertilized. No doubt the traders from Arabia have crossed all parts of northern Africa from the east to the centre, and they may even have reached the west coast, but no information could be obtained from them but the vaguest reports. Accepting these implicitly, and interpreting them naturally and without theory, there had been maps prepared during and since the middle ages, which are really as correct as any maps