We have already seen, that what Stackhouse considered as seeds, were probably capsules, as they burst asunder and discharged smaller'bodies. Turner makes the remark, that the seeds of different species have been observed to discharge very minute granular globules ; and with that candour and diffidence which distinguish the accurate ob server, he confesses his doubts whether the small bodies, generally accounted seeds, may not themselves be seed vessels. It may be remarked, indeed, that his representa tion of the bursting of a capsule, (Hist. Fuc. t. 181.), and his figure of a seed pouring out its contents, (t. 61.), bear the greatest resemblance to each other. The seeds of fuci, in.gencral, must be very minute : they seem to abound im perceptibly in the sea, as the impalpable seeds of fungi, musci, and lichens, do in the air.
In most of the tuberculiferous fuci there are visible, be sides the seeds, and intermixed with them, numerous ellip tical pellucid granules, much more minute than the seeds ; together also with many small jointed fibres, among which the seeds and pellucid granules lie imbedded.
Duration of Fuci, and their Rapidity of Growth The fuci, like land plants, reach maturity in different spaces of time, and endure for different periods. Many of the smaller and more delicate are annual; others of the herbaceous kind seem to be biennial, or at least frequently perish at the end of the second season ; and many continue for several seasons. Those with stems of woody texture endure for a considerable number of years, in situations where they are protected from the violence of the waves during storms. Old stems of Focus digitatus are frequent ly to be observed, not only completely invested with para sitic fuci, confervx, and flustrx, like old trees with lichens and mosses, but with the epidermis and bark become split and rough, and loosened from the woody part of the stem.
The well known Focus saccharinus has been observed to renew its frond in a very curious way, the new growth proceeding from the base, and pushing before it the old frond after it has discharged its office, in the same way as the human nails are renewed. "The plant,'' observes Ala Turner," thus acquires a perennial growth, and as Tibul Ins beautifully says of the serpent, novas exult winos." It is the opinion of Mr Turner, that Focus agarum (t. 75.) re news its frond in the same way.
Jo judging whether a focus belongs to the class of an Duals or perennials, besides attending to the general struc ture and habit, Laniouroux has pointed out another mark : he has very commonly found, that those fuci, which bear their fructification on the branches, are perennial, while those which have it on the tips of the fronds are annual.
It is remarked by INIr Turner, that the smaller and more delicate sea-weeds produce their fruit in the beginning of autumn ; while the larger and coarser species prefer for this purpose the " stormy months of winter." But the ra pidity of growth of some of the large coriaceous kinds throughout the winter is wonderful, and it is believed has only of late been fully ascertained. The.facts shall there fore be stated with some minuteness of detail. They were observed in the course of the very arduous undertaking of erecting a stone-beacon on a low rock called the Carr, situ ated near the entrance of the Frith of Forth : and when we mention as the observer the distinguished civil engineer Air Stevenson, a man accustomed to habits of accurate ob servation, it is perhaps superfluous to add, that particular attention was bestowed at the request of the writer of this article, and specimens of the fuci transmitted to him. The
Carr Rock is about 20 feet broad, and 60 feet long : it is only uncovered at the lowest ebb of spring tides. It was completely clothed with the larger fuci, particularly Fucus esculentus and F. digitatus. In the course of autumn 1813, the workmen had succeeded in clearing out and levelling with the pick and axe a considerable part of the foundation of the intended beacon, when, in the beginning of Novem ber, the operations were necessarily abandoned for the win ter. At this time the rock was reduced to a bare state. The coating of sea-weed had at first been cut away by the workmen ; the roots or bases were afterwards trampled by their feet ; and much of the surface of the rock had been chiselled. Upon returning to the Carr in May 1814, in or der to recommence operations, it was matter of no slight surprise to find the surface again as completely invested with large sea-weeds as ever it was, although little more than six months had elapsed since the work had been left off, when, as already said, the rock was weed. In particular it was observed, that many newly produced spe cimens of Fucus esculentus measured six feet in length, and were already furnished with the small appendages near the base, or pinnx, which at maturity contain the seeds-of the plant. Lightfoot mentions four feet as the ordinary length of this focus, but adds, that it sometimes reaches nine feet. Those at the Carr Rock, therefore, were nearly full sized. The common tangle, F. digitatus, was general ly only about two feet long ; but this species when fully grown seldom exceeds three or four feet. It is to be ob served, that the specimens here alluded to were taken from that part of the surface of the rock which had been dressed off with the pick and chisel the preceding autumn, they had therefore grown from the seed ; and indeed it was re marked, in general, that the sea-weeds had grown more luxuriantly on the newly-dressed rock, which is sandstone, than from the old stools, which had been merely cut over, or trodden down by the workmen's feet. It appears, there fore, that the seeds of these fuci, floating about abundantly in the waters of the Filth of Forth, must have attached themselves to the dressed surface of the sandstone after the middle of November, and must have vegetated and increas ed with great rapidity during a winter remarkable for se verity : for this, it will be remembered, was the winter of the great frost, as it was stiled, which continued nearly the w hole of the month of January 1814, and of which a very full account will be found in the Scots Magazine for Febru ary of that year. Other circumstances, it may be observed, were here favourable to their growth. During the winter and spring months, the Carr Rock must have been almost constantly under water. The incessant struggle of the tides at Fifeness is calculated to produce that degree of agita tion which has long been considered favourable to the growth of the stronger sea-weeds ; and this does not seem to have been interrupted by the rolling of heavy waves for many weeks during winter.