Columbus and Lerius encountered most extensive banks of floating fuci in their adventurous voyage : they compare them to extensive inundated meadows, and complain of their impeding the progress of the vessels. So novel a scene produced no little consternation and alarm in the crew of the Santa Maria.
Detached patches of floating sea-weeds of various ex tent, but not deserving the name of banks or meadows, are met with in different parts of the Atlantic. Bonpland ob served such patches to the north of the Cape Verd Islands.
Linnams, speaking of Fucus natans in the Species Plan tarum, says, " Vegetabile, in fallor, inter omnia in orbe nu merosissimum." But under this title he included a con siderable number of species, indeeed all that generally oc cur in the " sea of sea-weeds." Turner was the first who effectually distributed the Linnxan Fucus natans into va rious species. He remarks that they form a tribe by them selves, though very clearly allied to the Fuci proprii of Weber and Mohr. Their leaves never in any case length ening into branches, and their vesicles being altogether empty, seem characteristic circumstances. It was formerly thought that these floating sea-weeds were natives of the Gulf of Mexico, and were carried across the Atlantic by the Great Stream : hence the common name of Gulf-weed. It is very evident, however, that the Gulf Stream would convey them rather to the Banks of Newfoundland than to the latitudes in which they usually occur ; and it could not in any case accumulate them to the south of the Azores.
There is no doubt that it was the opinion of Linnaeus that they vegetated in the ocean, and floated about without ever being attached. This notion is likewise now exploded. Several of the species and varieties have been found with roots or bases, and some have been gathered in their native place of growth, where they were fixed to the rocks. It appears likely that they grow on rocks, probably at very considerable depths, in the Atlantic, Pacific, and Indian Oceans, whence they arc carried, among other rejecta menta of the seas, to the shores of almost every country, accumulating however on the surface of the ocean, in cer tain latitudes, owing to prevailing winds and currents. Some are inclined to think, that, being torn from their na tive rocks before they attain maturity, they perfect their seeds while in a floating state; and it seems not unlikely that this may sometimes be the case. M. Humboldt, how
ever,is of a different opinion : he thinks that vegetation can scarcely continue for a longer time in a detached floating sea-weed, than it would do in the branch of a tree torn from its trunk ; and he considers these floating fields as com posed of plants which have passed maturity.
It is certainly very difficult to explain why great moving masses of marine plants should be found for ages nearly in the same local positions. When decaying, they may in deed be supposed to be carried away by the equinoctial currents; which may scatter them even towards the coasts of France and Norway. But how the fresh weed is suppli ed ; by what causes it is detached from depths perhaps of forty or sixty fathoms, where it is generally thought the sea scarcely suffers agitation, are problems which remain to be solved. Lamouroux indeed states, that although fuci adhere firmly before the fructification appears, they sepa rate very readily after this period; and Humboldt remarks, that fish and mulluscous animals, by gnawing their stems, may also contribute to detach them.
The spherical vesicles, supported on flat stalks, and re sembling juniper berries, interspersed on the stem and branches of the plants, were erroneously regarded by Lin nmus as the fructification ; but the true fructification, as ascertained by Turner, occurs in the form of cylindrical receptacles on the branches, inclosing globular tubercles, which again contain the seeds. It may be noticed, that Don Hippolyto Ruiz, in his Flora of Peru, and in his pam phlet, "De vera Fuci natantis Fructfficatione," described the sexual organs of the floating sea-weeds in a manner that surprised botanists in general. Stamens and pistils were declared to be as obvious in this fucus as in most of the phxnogamous vegetables ! But the observations of M. Bonpland rectified the mistake of Ruiz. Certain appen dages, in the form of little cups and feathers, which he took for the parts of fructification, were found, on close exami nation, to be nothing else than parasitical zoophytes be longing to the family of ceratophyta. When dried, they effervesced with acids, as the calcareous substance of any common sertularia or flustra would do.