for weeks together the bands of brave adventurers who have tried to penetrate to the "open sea." All the desolate desert of snow would be as empty of human life as the sand wastes of Sahara if it were not for these insignificant vegetable forms, from which they directly or indirectly get their food.

CHAPTER IV.

LIVERWORTS AND MOSSES.

HERE seems to be in Nature some wonderful

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healing power which expresses itself in the most widely spread, even though they be the humblest, of her manifestations. Not more tenderly does the mother's hand cover with brightness and beauty the grave that holds her buried love and hope, than Nature heals over with creeping mosses and graceful ferns the unseemly wounds which man so ruthlessly makes in our beautiful earth. It sometimes seems as if nowhere was such scope given for the lavish expenditure of her resources, as that afforded by some such vandalism.

There is no form of organic life which reveals more that is wonderful and beautiful than does such humble life when subjected to the test of the microscope. Almost the first thing which presented itself as I opened the pages of Carpenter with the happy sense of possession, was the exquisite little bird's-nest cup with its treasure of gemmæ, which

may be seen in Fig. 31. Its beauty naturally created the desire to find the wonder itself, and to subject it to microscopic scrutiny. On one of our loveliest October days,-when Nature was holding her Carnival preparatory to her long and cheerless Lent, a pilgrimage for this purpose was planned, and carried into execution; and a spot, loved of the liverworts, mosses, and ferns was found.

A walk over unequal railroad ties, with the usual roadside accompaniments of wretched Irish hovels and their hideous and disorderly surroundings, was hardly the tuning up one needed to fall quietly into. the mood appropriate to an introduction into the fairy court where myriads of tiny creeping plants and waving fronds of fern were keeping gala-day. ·

Just by the side of the railway track rose a tall perpendicular bank of rock. The strata projecting here and there, after the rough handling of the pickaxe, afforded foothold to myriad forms of life. From the base to the crown of the artificial cliff, every square yard was covered with verdure; and over and through it all, the perpetual dripping of a gently running stream supplied the constant moisture in which such life delights, and without which it pines away and perishes.

In one of the horizontal ledges near the foot of the cliff, the patient water had hollowed out for itself a tiny basin which it forever filled and forever overflowed. Around this spring, every inch of rock was covered with the curling fronds of the Marchantia polymorpha, each leaf clinging close to the bare rock by a thousand little rootlets. This was the very plant we were hoping to find; it is perhaps the commonest, and is certainly the most interesting, of the class called liverworts in the vernacular tongue, and hepaticæ by the botanists. It was one of those days when every thing went harmoniously; when matter seemed to have gotten the better of its "natural depravity," and to be all that, ideally, it should be. In spite of the lateness of the season, there were the flattened fronds with their curled-up edges; bearing upon tiny stalks which rose from the middle vein of the leaf, the female portion of the plant-the archegonial disks-in full and vigorous life [Fig. 24, A, a]. Upon the same frond, the cupules (A, b, b), holding their gemmæ or spores, were found in every stage of development. only thing that was wanting was the antheridia. The cupules bearing the gemmæ, instead of being sessile upon the fronds, as they are given in all the

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figures which are commonly found, were, in the specimens examined, raised upon a small pedestal; the gemmæ themselves, however, were identical with those drawn by Sachs [Fig. 31].

A, a, Archegonial disks; b, cupules bearing gemmæ ; c, root-hairs. [From Nature.]

Hitherto, in our ascending series, we have examined no organisms of a very complex nature. The cells have been sometimes simple cellulose sacs, with their protoplasmic contents; sometimes an association, more or less complex, of such cells. There has been no considerable differentiation among them; they have been, in fact, like independent savages, sometimes living separately and performing, each one for itself, all the functions of life; or else they have been banded together for mutal protection.

The Marchantia give more than one striking illus