mination, not only to correct the mistakes of others who did not possess similar advantages, but also to furnish such accurate descriptions as will prevent all future errors. Many ladies, indeed, have been very eminent in this department of Botany. Dr. Greville alludes to this pleasing fact in the introduction to his work on the British Alga. "It is not without a feeling of extreme pleasure," says he, "that, by means of the present work, I shall place in the hands of my fair and intelligent countrywomen a guide to some of the wonders of the great deep; nor need I be ashamed to confess that I have kept them in view during the whole undertaking. To them we are indebted to much of what we know upon the subject. The very beauty and delicacy of the objects have ever attracted their attention; and who will deny the rationality of that admiration which is expended on the works of an Almighty hand, or censure as trifling the collecting of things, even in the absence of information concerning them, which, if contemplated as they ought to be, can only tend to refine the mind and raise its sentiments?"

The larger plant is the Coralline Griffithsia (Griffithsia corallina), of a bright pink colour, the

partitions of which in the main stems are well marked by the swollen joints, which give the plant the beaded appearance of a coralline, whence its

name.

GRIFFITHSIA CORALLINA.

These joints, when the plant is dried, are dark, from the colouring matter of the other part having been discharged, as I shall explain to you

S

by and bye, and they become gradually shorter in the smaller branches. Age and exposure to the sun affect the colour very much; it becomes lighter, and is often tinged with green. In drying it frequently loses much of its colour, and the paper, to which it adheres very firmly, is often tinged with a beautiful carmine, which will remain unchanged for years.

The Bristly Griffithsia (Griffithsia setacea) is a more rigid plant than the former, and grows in thick bunches from four to five inches in length: the colour is a rich crimson, very fugitive, which exposure to the air will change to a dirty orange. This, like the last, gives out its colour in fresh water, and no doubt a fine lake could be obtained from it, could it be procured in a sufficient quantity.

Griffithsia setacea, when first gathered, possesses a considerable degree of rigidity or firmness, but, after being immersed in fresh water for a short time, loses that firmness, and becomes flaccid. Not only does it undergo these changes, but when it has been in the fresh water for a short time, it makes a crackling noise like a weak spark from an electrical machine, or as salt does when thrown

into the fire. Dr. Drummond of Belfast has given the following interesting account of his experiments upon this plant :—

I poured some fresh water on a common white plate to the depth of about one twelfth part of an inch, and in this I put a portion of this plant quite fresh from the shore. It remained for several minutes quite still, and then some of the divisions of the frond exhibited sudden startings like spasms. I had repeatedly before been amused by watching this appearance on a larger scale, though with the naked eye, by putting a bunch of the plant in a basin of water. When so placed it soon assumes the appearance, to a considerable degree, of being animated; instantaneous startings are observed in the chief branches, along with lateral motions of the smaller branches, which are seen to move towards or to diverge from the former.

"But the cause of these startings, and of the consequent motions of the branchlets, was more obvious, by observing what passed in a portion of the plant laid in a thin stratum of water on a plate, as above alluded to. Whenever the startings took place, a change began to take place also in the colour.

The joints of the plant are filled

with the coloured fluid, and while it is in the salt water the partitions (septa) between the joints remain entire; but when the influence of the fresh water is felt, the partitions burst, and the contents of one joint are exploded into the next, the colouring matter at the same time losing its uniform tint and curdling into grains. From the violence with which the contained fluids are urged through the partitions in the joints, breaches form in the sides, also, of some of them, and then at every new spasm a quantity of the colouring-matter is hurried through these breaches into the water. The latter explosions present under a common magnifier an extremely interesting appearance. They are instantaneous, and when the projected fluid has attained its extreme distance, the colouring-matter suddenly settles in a crowd of dark grains, so as to give not an unlively idea of a bomb-shell in the act of bursting. Sometimes several of these occur in rapid succession, and again half a minute or more intervenes between them."

The pink weed, which covers with such profusion the sides of this shallow pool, and spreads, indeed, over the bottom of it, is the Common Coral