Although this book bears every where the marks of its author's genius, yet it is impoffible not to obferve when reading it, that towards the end he begins to flag, and we fee with regret, what effects piety when difturbed by fanaticifm can produce on a mind exhaufted by application.

PAGE 22, 1. 24.

*Such are the affiftances. Since the days of the author many excellent works have been published on infects, particularly after the fyftem of Linneaus appeared, which not only difpelled the chaos that hung over the whole class, but clearly gave the definition of an infect which had not been done before. Germany especially is rich in publications on this fubject, which are too numerous to be mentioned here. In England the chief are the Aurelian, or a Natural History of English infects by M. Harris. LOND folio, 1766. Illustrations of Natural History by D. Drury, 4to LOND 1771, &c.— Barbut's Genera Infectorum; 4to. The English Entomologift, exhibiting all the Coleopterous infects found in England; by Thomas Martyn, LOND. 1792. In France a very fplendid work was begun, intitled Entomologie, ou Histoire Naturelle des Infectes, of which two large 4to volumes were published before the Revolution, containing Coleoptera only. PAGE 25, 1. 10.

I will endeavour to difpofe my reader. These words are truly worthy of a Christian Philosopher. This is the proper end which a person ought to propose to himself in the study of the works of nature, which, without it, is nothing but vain curiofity. We commit an outrage on the Being of Beings, when we fet ourselves to contemplate his wonders, without deigning to lift our eyes to their author. As every thing proclaims his greatness, and every thing bears the marks of his wifdom and infinite power, it is blindness not to acknowledge him, and it is criminal to acknowledge him without at the fame time paying him the tribute of our worship and adoration. PAGE 28, 1. 29.

A flea never can produce a wasp. A person uninstructed in natural history, feeing that one fpecies of maggot fometimes produces different forts of flies; and that often feveral forts of flies proceed from one caterpillar which naturally produces a butterfly, would be led to think that there was nothing but declamation in what the author has advanced and no truth in it. But he would be wrong to judge in this

manner. These productions, fo monftrous and fo uncouth in appearance, are not on that account the lefs fubject to the conftant and general law of nature, that each animal produces its like. If we often fee infects of the fame fpecies, proceeding from animals of a very different kind, it is not that the latter have generated the former; but the females of the one having introduced their eggs into the bodies of the others, the young have been produced from these eggs, and after having fed on the fubftance of the animal in whofe body they were inclofed, iffue from it in the form of the infects that had placed them there. These are facts now univerfally known, and which I have verified by experiments not neceffary here to be detailed.

PAGE 28, 1. 33.

They cannot repair the lofs. This appears fo certain, and is fo conformable to the ideas we have of the formation of organifed bodies, that one would not expect to find exceptions to the rule. But the author of nature, whose wisdom confounds all our reafoning, in order, as it would feem, to fhew us how little we ought to depend on our own powers when we judge of his operations, has created animals which form a very remarkable exception to it, having the fingular faculty of reproducing their members whenever they are deprived of them. Sea ftars, crabs and lobsters are inftances of this, which cannot now be doubted, after what has been related by a naturalift of fuperior abilities, in the Memoirs of the Royal Academy of Sciences, for the year 1712.

But thefe inftances, and others which I might mention, by no means affect Mr Leffer's reafoning. It is not the sea ftar, the crab or the lobster that replace the limb they have loft; it is nature which gives it to them, and they contribute as little to the reproduction as we do to that of our nails or our hair.

PAGE 30, I. 3.

They multiply by generation. It is a general law of nature that animals preferve their fpecies, and multiply in the way of generation. This has never been doubted as to the larger animals, and when infects have been narrowly examined, it has been found that even they whofe production feemed the moft equivocal, owe likewife their origin to the u nion of a male and female of the fame fpecies. But how ever general this rule may be, the univerfality of it is not

yet

yet established. The various ways in which propagation is feen to take place among infects, feem to authorize a doubt on this fubject. There are feveral forts of those animals formerly claffed among infects, fuch as fnails and earth-worms, which are both male and female in one individual. We find among true infects certain fpecies, the greater part of which are neither male nor female, as bees, wafps and ants. Some are obferved to engender without coupling, the male contenting himself with depofiting his femen on the eggs of the female, as in the Ephemera. Some are found which can produce a pofterity for feveral generations by a fingle embrace, as I have discovered to be the cafe with the aphides. If we believe Swammerdam on this head, who however gives no folid proof of his opinion, there are fome females among infects which can be impregnated by the mere fimell of the male. All these various methods of propagation, lead us to prefume that there may be infects which multiply without reciprocal intercourse, and without the procefs of generation ftrictly fo called, and where a fingle individual, by the exertion of its own powers, is fufficient to propagate its kind; but hitherto no author as far as I know, has demonftrated the fact by a conclufive experiment. It is true that Leewenhoeck and Ceftoni thought they had discovered fuch a one among the aphides. Neither they, nor M. de Reaumur ever faw them coupling, or could difcover a male one among the whole fpecies; all they examined whether winged or not, were always females, and with young even before they had attained their natural fize. Thefe experiments feemed pretty decifive, and others made by me feem ftill more fo. Some aphides, taken away at the moment of their birth, and kept fecluded under glaffes, in eight or ten days produced young. Thefe young were likewife inftantly removed, and bred up in the fame folitude, produced others nearly after the fame period, and that production continued long enough to perfuade me, by reasons stronger than thofe of Leewenhoeck or Ceftoni, that their opinion was the true one. But having continued my experiments till the feafon when the leaves began to fall, and not having any farther doubt on the fubject, I was all at once undeceived, when I least expected it. I had collected all the young which my folitary aphides had produced, and had eftablished a little colony of them on the extremity of the branch of a willow which kept fresh in a glafs of water. The cold had already made the leaves to wither; but feveral of the aphides in the nymph

nymph ftate, maintained themfelves on it with the reft, and arrived at their perfect form. One day as I was vifiting them according to custom, I found one of those with wings, fitting on one without wings. 1 confidered this pofition at firft as the effect of chance, but the tranquillity of the winged aphis, while the other, disturbed at my approach, was running up and down, made me fufpect fomething. I took a magnifying glafs, and upon a near examination, found that the pofterior part of the winged infect, bending down towards that of the other, was intimately connected with the under Part of it, and exhibited marks of an union in the common form. This attachment lafted more than an hour, after which the winged infect flew away. I faw the fame thing happen to many others of the colony, who formed a connection like the firit; and what perfuaded me that it was a true connubial intercourfe was, that having accidentally crushed two of them in that fituation, while I was examining two others, I found after their death, the extremities of their abdomen ftill attached. The notion therefore of there being animals which can individually propagate their species is not yet cftablished by experiments made on the aphides: let us fee if it is better founded on those that have been made on the mufcles of fresh waters.

Monfieur Mery in the Memoirs of the Royal Academy of Sciences for the year 1710, afferts that it is. He has obferved four parts in this animal that may ferve for generation: two of these he calls ovaria, because they contain eggs, and two he calls veficula feminales, because in his opinion they contain the fenen, which is white, and of the appearance of milk. Their ftructure appears fimilar, all four terminate in the anus, where he says that the two principal ones, as they go out, are united, which is fufficient for generation; and as he has obferved in this animal, neither male nor female organ, he thinks himself the more authorized to conclude that it is androgynous. But this reafoning, however just it may feem, it is not fo conclufive as M. Mery imagines. The parts which characterise the sexes, may be fo difguifed by their flexibility, by their fituation and form, in an animal whofe figure is fo anomalous as the mufcle, that it is not impoffible but he may have seen them without knowing them; and even though they were actually not to be found, it would not prove that each mufcle was of both fexes. Neither male nor female organ is to be observed in the greater part of fiflies, but are they on that ac

Count

count both male and female? Befides, though two veffels of the four which terminate in the anus of the muscle, are receptacles of its eggs, it does not follow that the other two are the refervoirs of the femen. The milky fluid they contain, may be deftined to another ufe, than that of fructifying the eggs; it may ferve to fix them to the bodies on which the animal depofits them; to envelope them with a fubftance which may defend them against the immediate action of the water, to afford the young, upon iffuing from the egg, a suitable aliment. The eggs of many aquatic infects are furrounded with a clammy matter which they probably owe to fuch veffels. The glue which makes the eggs of butterflies adhere to the bodies on which we see them fixed, proceeds from two veffels terminating in the rectum, and containing a vifcid humour, which is any thing but femen; why then should thofe of muscles contain it? But even tho' they fhould contain it, would it follow that muscles were individually fufficient for their own multiplication? By no means. The female butterflies have receptacles which contain femen, and that femen alone is able to fecundate their eggs; thefe rcceptacles alfo terminate in the rectum, and inundate the eggs in their paffage. But notwithstanding this,thefe butterflies muft enjoy the company of the male, for it is the male alone who furnishes this femen. May this not allo be the cafe with the river muscles?

If it were certain that the pholades never leave the hole they form for themselves at the inftant of their birth, as M. de Reaumur maintains, on very plaufible grounds Mem. of the Royal Academy of Sciences 1712) one would be temp ted to believe that these fhell-fifh were iufficient of themfelves for procreation, if we did not rather chufe to suppose that their impregnation took place while they were yet in the matrix of their mother, a circumftance we are not hitherto acquainted with an inftance of; or perhaps that they have males of another form, and more active than themfelves, which vifit them in their retreats, as it happens to the gall infects. But if facts fo fingular as that in question, could be established by mere reatoning, no animal would better deferve to be put among the number of those which are fufficient of themselves to multiply the fpecies than that worm of the human body called Tenia, the longeft perhaps of all animals, fince fome of them have been found eighty yards in length, and it is not certain but that fome of them may be ftill

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