66 IN THE BEGINNING."

51

to trace them, as may frequently be done, above the present sea-mark, into fossil beds filled with the remains of existing species. Following up these deposits further, we gradually find, by the introduction of new forms which no longer exist in a living state on our shores, that we are challenging the videttes which stand sentinel to another territory, inhabited by a different race of beings. And thus we are led, step by step, and often insensibly, far back into the dreamy regions of the early history of our planet; into times and seasons when the sun looked down on no dwelling of man, but when his beams gave life to countless tribes of creatures whose race is now run, and whose half-told tale is found written in the earth or the rock. If their race be extinct and their glory departed, at least they live in marble, and human greatness can often boast no more. Finally, we reach a time when the waves of a primeval sea sounded hollow on a

naked shore, and no ear listened to their music.

66

Sky, sun, and sea, were all the universe;
The sky, one blue interminable arch,
Without a breeze, a wing, a cloud: the sun
Sole in the firmament, but in the deep
Redoubled; where the circle of the sea,
Invisible with calmness, seemed to lie,
Within the hollow of a lower heaven."

MONTGOMERY.

CHAPTER III.

THE ROCKY SEA-SHORE-SEA-WEEDS.

THE success of a marine-botanist, or Algologist, on a rocky coast will depend more on the extent of surface uncovered at low water mark, and on the outward conformation of the rocks of which the tidal margin is composed, than on the geological structure of the district. Soil in some measure affects the vegetation of the sea, but not to any great extent. The roots of sea-plants bear little resemblance to those of land plants. Few are fibrous, and few indeed send out extensive bundles of fibres to seek through a varying soil the substances necessary for their perfect growth. The roots of seaweeds must be regarded more in the nature of holdfasts,

destined to keep the vegetable fixed in a proper locality, than as separate organs contributing to the nourishment of the body. With this end in view, nature furnishes sea-weeds, in the great majority of instances, with a simple conical disc, by which they strongly adhere to the smoothest surface; and when a more root-like holdfast

is given, it is merely a multiplication of such discs, or a strengthening by lateral ropes the original gripe taken of the rock. Roots of this nature may be seen in the large oar-weeds (Laminaria) of our coasts, particularly in the L. digitata, a species with a long cylindrical walking-stick-stem, crowned with a broad leaf, cloven into a great number of ribbon-like segments. In this plant, while young, the root consists of a few rudimentary processes as it advances in growth, and as new props are required to support the additional weight, the branches of the root lengthen and others are gradually

54

ROOTS OF SEA-WEEDS ACT AS HOLDFASTS.

added, till a compact mass of interwoven fibres is formed, each of which takes a separate gripe of the rock, by the disc at its extremity, and all combined form a conical mass, representing the simple disc of the Fuci and most other sea-weeds. On some sandy shores, there are seaweeds with much more extensive roots,-roots that resemble those of grasses which cover sand-downs, extending to a considerable depth in the sand, branching out in every direction, and forming a compact bed of fibres, and a firm foundation for the vegetation. Such roots are obviously induced by the nature of the soil on which the plant grows, and would be superfluous on a rocky bottom.

The roots of sea-weeds seem to be little concerned in the active growth of the vegetable, except in the earlier stages. Like all the lower vegetables included in the class Cryptogamia, the sea-weeds are composed of a simple aggregation of cells, which form a more or less homogeneous body through which fluids freely pass, and whose whole surface absorbs nourishment from the surrounding water. This is the reason why the geologi

*

cal nature of the district has little relation to that of the marine vegetation which clothes the rocks. But the character of this vegetation is greatly varied by the outward form of the rocky masses. Thus, on a shore com

A cell, in botanical language, means a little bag-like body, composed of membrane, and containing a living substance capable of spontaneous growth by multiplication or division of its parts. Of such little bodies, millions of which may be contained within a cubic inch, all the soft parts of vegetables are composed. In sea-weeds the cells are often of large size.

posed of granite-rocks, where the masses are rounded and lumpy, with few interstices or cavities in which water will constantly lie; and presenting to the waves sloping ridges along which the water freely runs up and down, very few species of sea-weeds, and these only of the coarsest kinds, are commonly to be met with. And thus the vegetation of granitic shores may be characterised as poor. But this poverty is owing altogether to outward form. For, wherever the granite affords a tolerably flat surface, interspersed with deep cavities in which pools of water are constantly maintained, a vegetation will be found as varied and copious as on stratified shores of a totally different composition of rock. The best localities are those in which there are the greatest number of rock-pools of moderate extent, with perpendicular sides, and a depth varying from one to three feet. Pools of this character, though situated near high-water mark, so as to communicate with the sea only when the tide is near its height, often produce all the species which are considered to be characteristic of extreme low-water mark. Their depth is sufficient to keep the water at a sufficiently even temperature, and their steep sides afford that shade which the more delicate sea-weeds require. On chalky shores I have observed that sea-weeds are poor and few in number. And this I attribute chiefly to the general absence of such rock-pools, though no doubt the soft nature of the rock has its influence, and the white surface, reflecting a greater quantity of light than the more delicate Florideæ can endure, drives such species to a greater depth of water on chalky shores than on others, and thus beyond the influence of the tide or