ninety-four bottles, being a clear gain of nearly two hundred per cent.

Another great advantage result ing from this statement will appear by making it an article of store for shipping, or exportation; and I shall submit a few ideas tending to promote such a beneficial object, by doing it in large quantities; for which purpose sufficiently extensive premises must be fitted up, with a proper number of shelves, one above another, at a distance of about five inches.

The vessel for scalding the fruit in should be a long wooden trough - of six, eight, or ten feet in length, two or three in breadth, and one in

depth, fitted with laths across to keep the bottles upright, and from falling one against another; this trough of water to have the heat communicated to it by steam, through a pipe from a closed boiler at a little distance. The boiling water, wanted to fill the bottles with, may be conveyed through a pipe and cock over the trough, by which arrangement, many hundreds of bottles might be done in a short time. It may be prudent to observe, that this idea is only speculative, not having been actually practised, but at the same time seems to carry with it a great probability of success, and worthy the experiment."

"T

HE mathematical and physical class instructedMessrs. Lacepede, Vauquelin, and myself, to render an account of a memoir by M. Francis Delaroche on the air-bladder of fishes.

As several naturalists have been of late employed in directing their attention to the organ which is the object of this memoir, and to its functions, we do not think it will be improper to preface our report by a historical view of what has been said on the subject; a recapitulation for which M. Delaroche himself has furnished us with ample materials.

The air-vessel of fishes is too remarkable, it strikes the eye too forcibly on the first opening of the animal, and differs too much from every other organ, not to awaken the attention of naturalists; but,

like most objects in comparative anatomy, it has long produced more conjectures and hypotheses than exact observations and experi mental researches.

Rondelet confined himself to the observation, that it existed more constantly in fresh than in salt-water fishes, and that it probably serves to assist them in swimming.

Marcus Aurelius Severinus risks an opinion that the air of this vessel was produced along with the animal; which proves that he had never perceived any communication with it outwards.

Gauthier Needham (in 1668) was the first who entered into more detailed inquiries, and inserted them in a book, where no one would expect to find them; namely, De formato foetu. Adopting

the

the general idea of the utility of this bladder for swimming, he explained how flat fish are enabled to do without it; he described the two tunics of this organ, as well as the varieties of its form, and the origin of the canal of communication. He shews that the vessels are more abundant than are requisite for its own nutrition; that it is probable that some organic function is exercised by them, and that the blood contained in them has some connexion with the air: but judging that it would be difficult for the air to penetrate into it from without, in certain fishes, through substances which fill the stomach, he conjectured that this fluid is secreted there, and that it proceeds from thence into the stomach, where it assists in the process of digestion: he even points out the red bodies which operate this secretion in the snake.

Borelli explained in detail, in 1676, the method in which the bladder is used in swimming. He observed that fishes, whose airbladders burst, remain at the bottom of the water, as well as most of those which are naturally deprived of it; and concludes that it is intended to render the body of the fish sufficiently light to be in equilibrium with the water: he added, that by compressing the bladder, or by abandoning the air which it contains, to its elasticity, the fish can augment or diminish ita total specific gravity, and assist it in its ascent or descent. He supposed, that the canal which establishes in certain fishes a communication between the air-bladder and the stomach, must be a method of varying or renewing the quantity of air.

To conclude: he has neither described the varieties of the struc

ture of the bladder, nor determined in what fishes it exists, and those in which it is wanting.

Redi resumes the observations of Needham. He added some details on those fishes which have no airbladder, and on the red bodies in the interior of several of these organs. He also stated, that he had in vain sought for the canal of communication in certain sea-fishes; but he thought that it was his fault, and this opinion of the generality of the existence of the canal has even reigned to the present time among some others. These remarks of Redi are still to be found in a book entitled, Observations sur les Animaux vivans contenus dans les Animaux vivans. Florence, 1684.

Ray and Willoughby, without making fresh inquiries, and without deciding on the manner in which the air is introduced into the bladder, disputed the idea of this air being used in digestion, and reduced the bladder to its employment in swimming, according to the ideas of Borelli. They insisted on the muscles peculiar to certain vessels, and mistook for them the red bodies in the interior of some others.

The same opinion on the use of the bladder was supported by Preston, by Perrault, and by Petit. Perrault made the important observation, that there are fishes without any canal, and that it is in the latter that the red bodies are found, which are intended for the separation of the air. He added, that in those which have a canal,the air does not issue from the bladder, although it be compressed; a remark too much generalized.

Petit, on the contrary, thought he had discovered in the canal of the carp,valvuli which admit of the

air escaping, but not of returnIng.

Notwithstanding the observation of Perrault, Artedi still ascribed to all bladders a canal destined, according to him, for the introduction of air: but, with the exception of Borelli's, there is no opinion given respecting their use.

It is the same case with Gouan, Bloch, and a variety of other authors, who add nothing in other respects to the details previously acquired.

But, admitting in its fullest extent this chief employment of the air-bladder, we might still suppose it to have accessory uses, and in particular we must defer giving any opinion as to the origin of the air which it contains.

This was the conduct pursued by Vicq d'Azyr in 1773. He imagined that the air originated in the stomach, from whence it entered charged with nutritive particles, into the air-bladder, in order to be absorbed by the vascular system, He was followed by Brousonnet in this idea under some modifications.

Erxleben entertained the same idea respecting the propagation of the air; but as to its uses he followed the common opinion.

These three anatomists seem to have been ignorant that the communication between the stomach and the air-bladder is frequently wanting.

This is strongly insisted upon by Kohlreuter in an anatomical description of the lotus. After having ascertained the defect in the canal, and that a number of other fishes are also without it, and after having described the organization of the red bodies, he maintained that the air is separated from the blood in the bladder. He thought his system was new, not having

read the writings of Perrault and Needham.

Leske adopted the opinion of Kohlreuter.

Monro, who in his work on fishes, ought to have thrown a great deal of light on this subject, has added but little to what was known before on this subject. He made the same distinction with Perrault between bladders with secretory red bodies which have no canal, and those which have a canal and want these bodies; but ha does not mention any French anatomist; perhaps because he had never read any of their works on the subject.

He remarked that the genus anguilla formed an exception to the rule, from having the canal and red bodies. With respect to the other parts of the question, he did not decide upon the use of the bladder; and merely inquired, if fishes could not, in swallowing, distinguish the bubbles of air from the mass of water, and make them pass in preference into this organ.

M. Fischer, now professor at Moscow, published in 1795, at Leipsic, a particular dissertation on this subject; in which, after having given an extract of the writings of his predecessors, and having communicated his own observations on the carp and the tench, he hazarded the opinion, that the airbladder, independent of its uses for motion, is also a supplementary or gan of respiration, destined to absorb the oxygen from the atmospheric air contained in water, as the gills are destined, according to him, to absorb the oxygen of the water itself, by decomposing it.

M. de Lacepede supposes, that certain fishes may at least fill their bladder with the gases resulting from the decompositions which

their respiration occasions. He thought that it was frequently hydrogen with which it was filled, and he mentioned tenches in which he had collected precisely this kind of gas.

Finally, M. Duvernoy, editor of that part of Cuvier's comparative anatomy which has for its object the air-bladder of fishes, adopted, in common with M. Cuvier, the opinion of Needham and Kahlreuter, that the air is produced in the bladder by secretion. He also described some of the organs of this secretion in fishes not before observed; but, from too much precipitation, he forgot to advance the principal argument, founded on the absence of all canal of communication in many species. He concludes, from the absence of the vessel itself, in fishes belonging indiscriminately to all descriptions of families, and even to genera the other species of which are furnished with it, that its functions cannot be very essential to life. By comparing its proportional volume with the nature of the movements of every fish, and by examining the supplementary means grauted to those who have it not, and the various effects of those means, he arrives at the conclusion, that it is essentially an organ connected with loco-motion.

He expresses his astonishment at the discordance between the analysis hitherto given of the air contained in this bladder; some like M. Fourcroy, having found hardly any thing but azote; others, like M. Configliati, having found so much as 40.0 of oxygen; while others, like Mr. Broadbelt, found the quantity variable in the same kind of fish according to circumstances. M. Duvernoy concludes with suggesting, that chemists should it

quire into the causes and limits of these variations; a precise knowledge of which could alone decide a great number of the questions in dispute.

Messrs. Geoffroy and Vauquelin on one hand, and M. Biot on the other, have recently made a great part of the experiments which were pointed out as requisite by M. Duvernoy.

M. Biot, in his first voyage to Ivica, examined the air in the bladder of several fishes of the Mediterranean, and found that it varied from pure azote up to 87.0 of oxygen, with very little carbonic acid, and without any hydrogen; and that in general the oxygen is the more abundant, in comparison to the azote, as the fish comes from a greater depth, although the water at these great depths does not contsin purer air than that which is at the surface.

He also made the curious observation, that in fishes suddenly drawn from a great depth, the airbladder ceasing to be compressed by the enormous column of water which bore upon it, is dilated so suddenly, that it tears the intestines, and is ejected from the mouth. As to the origin of the air contained in it, he seems to think it has been secreted.

The experiments of Mess. Vanquelin and Geoffroy, published by M. Biot, confirm his own on the subject, so far as the fishes on which they were made, living in our fresh waters and at very small depths, gave but very little oxygen. They agree also with other more ancient experiments of M. Fourcroy, who had found nothing in the bladder of the carp but azote al most pure, and with the analysis made by M. Humboldt of the air in the bladder of the gymnotus

electricus,

electricus, which consisted of 96.0 of azote, and 40.0 of oxygen.

Such was the whole of our knowledge of the air-bladder of fishes when M. Delaroche read his memoir to the Institute. But in order to complete the series of facts which are necessary to guide us in forming an opinion of his theory, we think it right to say a few words upon two memoirs published since.

One of these, by M. Geoffroy, refers to an earlier memoir, in which he developes, anatomically, the means by which the fish compresses or relaxes its bladder, in order to descend or ascend. Indeed, he says at the same time, in the introduction of his memoir, that the bladder is by no means an organ of motion by itself; but this is because he thought that those who regarded it as such, suppose that it is dilated by the increase of the air which it contains, and vice versâ, an opinion which no person seems to have entertained; for it is always by the action of the muscles that it has been made to be compressed or dilated: on this subject, therefore, M. Geoffroy is really of the opinion of Borelli, which is the commonly received idea.

The other memoir to which we have alluded, is by Messrs. Humboldt and Provençal, and has for its chief object the respiration of fishes; but these authors have naturally been led to examine the air in the swimming-bladder.

They operated upon river fishes, and found the air variable in composition from 99.0 of azote to $7.0. They have observed as much as 5.0 of carbonic acid. They made some tench respire hydrogen, and yet their air-bladders when examined exhibited none; by keep

ing them in oxygen, however, the proportion of the oxygen in the bladder was somewhat increased. On removing the bladder from them, they were not prevented from producing, by their respiration, the ordinary effects upon the atmosphere; they were even able to raise themselves in the water, although they generally remained at the bottom of the vessel.

Thus, in the numerous works we have analyzed, almost every possible hypothesis has been proposed, attacked, or defended, and examples have been given of almost all the combinations of organization that could be devised. M. Delaroche had only therefore to examine these organizations a little further, in order to reduce them to general rules, and to weigh over again the arguments advanced for or against every hypothesis.

Let us see how he has acquitted himself of this task.

His residence at Ivica, Formentero, and on the coast of Spain, with Messrs. Biot and Arrago, having furnished him with oppor tunities of examining a great number of Mediterranean fishes not to be seen any where else, and their air-bladders having chiefly occupied his attention, he continued his inquiries after his return, on our common fresh and salt water fishes: hence he has furnished upwards of fifty particular descriptions of the air-bladders of as many species of fish, several of which have not hitherto been described. These descriptions added to those which former authors had given of some species which M. Delaroche could not find, form the materials of his present memoir; and he has placed his own at the end of the work, as so many proofs of

the