Bangia was named after Hoffman Bang, a Danish naturalist, who wrote a work on the Conferrer. It has a flat, capillary, membranaceoue frond, of a green, reddish, or purple colour.
The order Oscillatoriaeece is composed of plants which are green or brown in colour, with continuous tubular filaments, seldom branched, though often joined together so as to appear branched. The fructifi cation consists of an internal mass divided by transverse septa, finally separating into roundish or lenticular sporidia. This tribe of plants, like the others, is found wherever there is water, and is more abundant in fresh water than in the sea. There are however many of them fonnd in the see, and also in mineral-waters. Many of the species, especially of Oscillatoria, are endowed with a power of moving so apparently spontaneous, that some naturalists have placed them among animals, as well as the more minute forms of plants belonging to the order Alga. Captain Carmichael, who devoted much attention to this subject, has made the, following observations, which were published from among his MSS. by Mr. Harvey :—" I have been induced to bestow considerable attention on such of the species as fell under my notice, on account of the singular motion remarked in the filaments by various naturalists ; and I do confess than the result is something like conviction that they belong rather to the animal than to the vegetable kingdom. This motion or oscillation has been attributed to various causes—to the rapidity of growth, to the action of the light, or to the agitation of the water in which the specimens were immersed for inspection ; but none of these afford a satisfactory explanation.. The last may be put to the proof by a very simple con trivance. Let a small portion of the stratum be placed in a watch glass nearly filled with water, and covered with a circular film of talc, so that its edge may touch the glass ; the water will be rendered as fixed as if it was a piece of ice. The glass may now be placed under the microscope, and the oacillation of the filaments viewed without any risk of disturbance from the agitation of the water. By following this course it will be speedily perceived that the motion in question is entirely independent of that cause. The action of light as a cause of motion cannot be disproved, because we cannot view our specimens in the dark ; but indirectly there is nothing easier. If a watch-glass charged as above be laid aside for a night, it will be found that by next morning not only a considerable radiation has taken place, but that multitudes of the filaments have entirely eScaped from the stratum; both indicating motion independent of light Rapidity of growth will show itself in a prolongation of the filaments, but will not account for this oscillation to the right and left, and still less for thoir travelling in the course of a few hours to the distance of ten times their own length from the stratum. This last is a kind of motion unexampled, I believe, in the vegetable kingdom. There is another point in the natural history of the Oscillatorie(r, which favours the opinion that they are animalcules. It is the extremely limited term
of their existence. The community, if I may so call it, lives for several months ; but the individuals die off, and are succeeded by others with a rapidity to which there is no parallel among genuine plants. 1f a' small portion of stratum, say one-fourth of an inch in diameter, be left for three or four days in a watch-glass filled with water, the whole area of the glass will be found covered with a thin transparent pellicle or incipient stratum, derived from the filaments that had successively radiated and died in the course of that short period." There are several genera in the order Oscillcaoriaeece:—Stigonenta has cylindrical, cartilaginous, branched, inarticulate filaments, inclu ding granules ranged in transverse dotted rings. Seytonema has branched, flaccid, tough, continuous, tubular filaments, with brown er olive-coloured endochrome, which is transversely striated, and at length separates at the striae into lenticular sporidia. Calothrix has erect tufted or fasciculate filaments destitute of a mucous layer, fixed at the base, somewhat rigid, without oscillation. The tube is continuous, and the endochrome is at length dissolved into lenticular sporidia. Many of the species of Calothrix are parasitical on other plants. It is to this germs that the Comferra nivea of Dillwyn belongs. It is the Calothrix nivea of Agardh. This plant is remarkable for its habitat in springs impregnated with eulphuretted hydrogen. It was first found in the sulphur-springs of Croft in Yorkshire, by Dr. Willan, and has since been found by other observers. Dr. Daubeny found it in many of the sulphur-springs of the Continent, and Dr. Lankeeter collected specimens at Moffat, Harrowgate, Askern, and other places where there were springs impregnated with sulphuretted hydrogen. The decomposition of this plant, probably mixed with the remains of other organic beings inhabiting the springs, has led to the supposition that the springs in which it was found contained a pseudo-organic matter which has been called by the names of Baregine, zoogene, and glairine. This was the opinion of the late Professor Anglada ; but Dr. Lankester, having been able to form glairine by the decomposition of the filaments of Calothrix nivea, renders it probable that there are no compounds in mineral-waters, except the salts, which have not been derived from plants or animalcules inhabiting the waters. (`Annala of Nat. Hist,' 1841; Notice of Plants and Animals found in Sulphureous Waters,' by E. Lankeater, M.D.) The genus Lyngbya has free, flexible, elongated, continuous, decumbent filaments, destitute of a mucoua layer; the endochrome densely annulated, and separating at the annuli into lenticular aporidia. This genus was named after H. C. Lyngbye, a Danish botanist, and author of a work on the Alg(s of Denmark, Some of the species are very col:ninon. The L. ruuralis is found almost on every damp wall or walk, forming an intensely green stratum of indefinite extent, which is very conspicuous after a shower of rain. Other species are parasitic upon some of the Fuci and are found in the sea.