In the course of our ample account of Lamouroux's ar rangement, a number of particulars connected with the general history and physiology of these plants have been incidentally stated. There remain, however, several points deserving of further and separate consideration, particular ly their germination and growth, their general structure, and the nature of their fructification.
Notwithstanding the many observations ol late inquirers, in no department of natural history does there remain greater room for discovery, than in tracing the progress of living fuci. The habitat of the plants presents many difficulties. It is only in a few favourable situations, in calm weather, and at low ebb tides, that observations can be made, either as to the earliest appearance of the plants when germinating, or as to the progress of the fructifica tion, and shedding of the seeds in the mature plant. To afford any satisfactory information, individual plants must be watched, visited at every season of the year, and the ob servations must be continued for a series of years.
Germination and Fructlfication of Fuel.
Mr Stackhouse, we believe, is the only person who has succeeded in vegetating the seeds of fuci, or in convincing himself that he has done so ; for doubts have been started as to the accuracy of his experiments. So extremely minute are the real seeds, and so great is the liability to error from other seeds floating unperceived in the waters of the ocean, that to prosecute discovery in this way would probably be a hopeless task. It may be right, however, to state his mode of proceeding. He selected three species for his experiments, Fucus serratus, canaliculatus, and bifurcates, (by which last, F. tuberculatus is to be under stood.) He detached some specimens of these very care fully from the rocks, preserving their bases or roots unin jured. lie placed them in wide-mouthed jars, and changed the water every twelve hours, drawing it off by means of a syphon, to prevent agitation. In the course of a week he succeeded in procuring what he considered to be the seeds. These, when ripe, he says, burst asunder transversely in the middle, with a kind of explosion. They appear therefore to have been, in reality, capsules containing seeds. They were inclosed in a bright mucus, immiscible with sea wa ter, and likewise specifically heavier than it ; so that this mucus was calculated to serve the double purpose of car rying the seeds to the bottom, and fixing them to the rocks.
He thus ascertained that some marine plants scatter their seeds when ripe, without awaiting the decay of the frond. The next point was to cause the seeds to germinate. He took some pebbles and small fragments of rock from the beach, the surfaces of which he considered as having been thoroughly purified by friction ; and after having drained off the greater part of the water in the jars, he poured the re maining drops on the stones. He left them to dry for some time, that the seeds might fix themselves. He then placed the stones in wide-mouthed jars, and alternately sunk them for some hours in sea-water, and exposed them to the air and rain, in order to imitate their peculiar situation be tween high and low water mark. In less than a week, a thin membrane was discoverable on the stones, precisely on the spots where the drops of 'water containing the seeds had been poured, and where of course the seeds had lodged. This membrane gradually extended itself and became of a blackish olive colour. There at last appeared mucous pa pilh or buds coming up from the membrane. These buds were somewhat hollow in the centre, frosts whence a shoot pushed forth : in some instances they seemed to rise on a short thick footstalk, and in this case resembled minute pe zizm, favouring the supposition that other fuci besides F. loreus present at- their base the mushroom appearance, though on a very reduced scale.
Till within these few years, the fructification of the fuci was little known ; and even yet it is not by any means well understood. To the minute and accurate investigations of Mr Turner, Mr Hooker, Sir J. E. Smith, the late Miss Hutchins, and Mr Sowerby, jun. we are much indebted. But the fructification of the largest species in the world, F.
pyriferus and buccinalia, and even of sonic of the largest and most common British species, such as F. digitatus, filum, and aculeatus, still remains to be discovered. Of the nature of the fructtlication of the caulerpre, no conjec ture has hitherto been formed.