and derivations introduced, as you propose, at the end of the volume, will be of the greatest utility and advantage, for the purpose of ready reference at any time it may be required.-B. Coventry, July 12.

Having received several letters on this subject, all highly approving of the plan which we have hitherto adopted, we intend persevering in that plan.- Cond.

Ignis Fatuus.If I may be allowed to remark on the review of Murray's Researches, &c. (p. 156.), I would observe that I can certify the existence of the ignis fatuus, and also that it appears 66 as a glow of lambent flame." Two of these phenomena made their appearance on the evening of the 26th of October, 1823, on board the Sandwich packet, on our passage from the West Indies to England, when about 200 miles north of the Bahamas, and remained, one at the spindle of each mast-head, for about two hours; the atmosphere being in a very unsettled state, with rain and lightning. The one at the main-mast-head was rather brighter than the other, and, before disappearing, occasionally passed up and down the upper part of the mast, but never entirely disengaging itself, notwithstanding the heavy motion of the vessel.

On "the luminosity of the sea" I would just say, that its appearance previous to a storm is a very old observation amongst sailors. It is, however, I think, without foundation, as it is to be seen, more or less, all the year round, in the Carribean sea, where there are no storms but in the hurricane months. In the hand it has a kind of mucous feel. W. H., R. N., Yeovil. August 5.

The Spider. The remarks on the spider, in the review of Murray's Researches (p. 157.), were peculiarly interesting to me, as I have often held a leaf in my hand, to which a spider had fixed his line, and have seen the spider floating in the wind, at a great distance, and returning again with surprising velocity. It has often gone to so great a distance, that I have thought the line had broken, and yet he returned again upon this singuJarly strong and delicate web. One day last week I amused myself for more than an hour in observing the proceedings of a little spider, whose bag of eggs had been removed and restored. I do not feel quite sure as to the species, but, if I can ascertain that, I think it would make an interesting paragraph, to detail what I then observed.-A. A.

The late Mr. Sowerby. At p. 198., I have observed that some wellmeaning friend, desirous of doing a service to the memory of my lamented father, in claiming for him his share of the honour due for the execution of that national work the English Botany, has rather overshot the mark : Mr. Sowerby was not the author of any part of the text of English Botany (erroneously called English Flora). The work owed its origin to the circumstance of Mr. Sowerby having made a number of sketches of plants, to be introduced in the foregrounds of landscapes, which he was in the habit of painting from nature. These sketches were shown to various botanical friends, at whose suggestion the work was begun, with the valuable assistof Sir J. E. Smith; and the only descriptions that were not written by that gentleman, were supplied by the late Dr. Shaw. In addition to the praise due to Mr. Sowerby, for the excellence of the drawings and engravings in that work, some portion is due to him for the spirit of enterprise with which he carried it on; for, although he had to depend upon portrait-painting for the capital required, he still industriously and steadily pursued his expensive project, until it began to remunerate him (which was not for several years), and he finally brought up a numerous family to enjoy its profits, and lament the loss of one of the best of parents. I remain, Sir, &c. J. D. C. Sowerby. Museum, Mead-Place, Westminster Road, Aug. 11. 1828.

THE MAGAZINE

OF

NATURAL HISTORY.

NOVEMBER, 1828.

ART. I. On the Metamorphoses of the Reproductive Bodies of some Algae, said to possess successively an Animal and a Vegetable Existence. By A.

ONE of the most extraordinary opinions now supported by various naturalists, is that which maintains a twofold vitality in a certain class of bodies, or, in other words, both an animal and a vegetable existence. Some very celebrated names have lent their testimony to confirm this opinion, and it is asserted that many of their conclusions are the results of actual experiment. It is true, they do not assert that any individual body is at once both an animal and a vegetable, but they do assert that it passes from an animal to a vegetable state without disorganisation.

"There are phenomena, in the kingdom of nature," observes Professor Nees von Esenbeck (as quoted in the Annales des Sciences Naturelles), "which can hardly require too frequently repeated experiments, and which, when proved, demand the support of numerous recorded authorities. For, as the phenomena in question appear to contradict certain principles. admitted into the reigning systems, we often prefer rather to deny the conclusions of candid and experienced observers, than to receive what has hitherto been regarded as untenable by generally received authority.

"In this situation are placed all observations upon the transition, or metamorphosis, of vegetable life (which is characterised by immobility) into animal life (distinguished by motion); the moment when a being, arrived at the period of its existence, continues itself, as it were, by a new creation, and the animated embryo developes itself into a motionless vegetable."

VOL. I.- No. 4.

Among the naturalists who have laboured in this new and singular field, Professor Nees von Esenbeck must be placed foremost on the list, as he was the first to publish his observations, in a distinct manner, in the year 1814. Since that period, Treviranus, Ditmar, Agardh, Bory de Saint-Vincent, Gruithuisen, Carus, Gaillon, Desmazieres, and others, have endeavoured to substantiate the truth of the pheno

menon.

The tribe of Oscillatòriæ, forming a part of Agardh's great group of Confervöideæ, or jointed Algae, are well known to have derived their name from the oscillating motion of the filaments. Nothing is more easy than to perceive this motion, and the Oscillatòriæ, consequently, are held in a dubious point of view by all botanists. M. Vaucher, of Geneva, who published a Histoire des Conferves d'eau douce, noticed such a difference between the two extremities of the filaments in some species, that he denominates one the head, and the other the tail.

Professor Agardh, of Lund, who has directed his attention chiefly to the Algæ, published, a few years ago, an ingenious essay upon the metamorphoses of many species. To show how far he has carried his observations, it will be sufficient to mention that, in his I'cones Algàrum inéditæ, fasc. 1. t. 10., he has represented the vegetable form of Oscillatòria flexuòsa, and also the animalcules into which the filaments are at length converted.

There can be no doubt, that the colouring matter of the famous red snow (named Protocóccus nivalis by Agardh), brought from the arctic regions by Captain Ross and Captain Parry, is a true vegetable, belonging to the order Algæ. It grows upon limestone rocks, tufts of moss, dead leaves, and even on the bare soil. The singularity of the situation, however, in which it was first discovered, that of pure snow, gave rise to speculations regarding its origin. Professor Nees von Esenbeck was inclined to think that the minute red globules, of which the plant consists, were the vegetable state of bodies which had gone through a prior animal existence, and perhaps of atmospheric origin.

Baron Wrangel, who discovered the Protocóccus nivàlis growing upon limestone (without knowing at the time that it was the true red snow), studied it very carefully. He mentions that the red crust was soon detached when placed under water, and a number of much smaller globules, of a yellow or pale colour, made their appearance, of which the larger red globules seemed to be composed. After a lapse of three days the globules became animated, like infusory animalcules; they

swam about, and were frequently pursued and devoured by other Infusòria.

It is worthy of remark, that Agardh does not mention having observed any such motion in the globules; neither does Mr. Bauer: and Dr. Greville, who has published a very full history and analysis of the plant in his Cryptogamic Flora, did not perceive it. The appearance of vitality, therefore, in this instance, was probably owing to some illusion.

The most precise observations ever made upon this curious subject, are the recent ones by M. Franz Unger, of whose account it may be desirable to give a translation in his own words. In this country, the very idea of such metamorphoses is almost startling; and, at first, will probably be regarded as visionary, and rejected accordingly. I trust, however, the present article will have the effect of inducing a few individuals, at least, to commence a series of observations for themselves.

"I found," says M. Franz Unger, "near Vienna, in a ditch containing some clear water derived from the recent melting of the snow, a Conférva, which, after cleansing from the clay which surrounded it, I deposited in a glass vase, and placed in a window, where I could observe without disturbing it. This was on the 5th of March, 1826. Two days afterwards, I noticed the production of a crowd of new rámuli, several lines in height, and rising from the general mass like a fine green miniature sward. On the 9th, these filaments produced fructification in the form of a darker green globule at their summits, by which I knew my plant to be the Conférva dilatata var. of Roth, or the Ectospérma clavata of Vaucher.

"As I continued my observations, I happened to look at the surface of the water, and was not a little astonished to find it covered, especially towards the side of the vase, with minute globules, unequal both in colour and size. Many of them swam freely here and there, moving, at their option, in one way or another, retiring and approaching one another, gliding round globules that were motionless, stopping, and again setting themselves in motion exactly like animated beings.

"Conjecturing the identity of the green globules that possessed motion with those that had none, I immediately began to examine whence these infusory animalcules derived their origin, and what relation they bore to the green globules and the fructification of the Conférva.

"The next day I perceived a great number of the globules aggregated around the bubbles of gas disengaged from the Conférva, and floating at the surface. They were some of them of a dark green colour, and either round or elongated; others

more transparent, tumid, and with one or two appendages diverging from, or at right angles with each other; these were evidently plants in a state of germination: other globules, again, were oval, very dark at one extremity, and almost transparent at the other; these swam about freely.

"Within the space of one hour, I succeeded in tracing not only the diminution of vitality, and death of the Infusòria, but also the subsequent developement of the dead animals into germinating plants, in such a manner as to establish the truth of the fact. But, on the 12th of March, I had the pleasure of ascertaining distinctly the origin of these minute bodies. I undertook to observe, without interruption, one of the tubercles of fructification, which I have already mentioned as terminating the filaments, in order to discover what became of the green matter enclosed within it. I had observed it for the space of half an hour, when the following changes (fig. 160. abc d) became perceptible :

"The globule became gradually darker in its colour, and a little transparent at its extremity; in the middle it was evidently somewhat contracted, and had some trace of spontaneous motion. I could scarcely believe my eyes, when I perceived the contraction to become more decided, and a cavity to be formed at the base. The contraction at length divided the globule into two smaller globules, which moved spontaneously towards the summit. As the developements proceeded, the cavity and the uppermost globule became enlarged, while the inferior globule became diminished. The latter at length disappeared, and the remaining large globule escaped by a terminal orifice, ascending till it reached the surface of the water. The whole of this process occupied about thirty seconds; but, from subsequent observations, it may be stated generally to take up one minute."