these precautions, in the harveft of 1761 they found every 8oth grain affected, though this crop was lefs damaged than any other in the province. It appears from this fact, that the corn-butterfly is capable of a long flight. The following calculation will fhew the aftonishing multiplication of these infects, and confequently the ravages which they make where they have already eftablished themfelves, and with which all the neighbouring provinces are threat ened. Every female produces from 60 to go eggs, of which 75 is the medium; but let us fuppofe the number to be no more than 70. Let us fuppofe alfo, that of thefe 70 eggs, one half only produce females, which makes the number 35. This multiplied by 7c, the number of eggs laid by each, gives for the fecond brood from a fingle infect, 2450: the half of this number supposed to be females is 1225, which multiplied by 70, gives 85,750 for the third brood. Half of this number 42,875, multiplied by 70, gives for the fourth brood 3,001,250; half of this 1,500,625, multiplied by 70, gives 105,043,750 for the fifth brood: fo that, fuppofing five broods in a year, each female butterfly of this fpecies that exifts in May, produces, before the May following, no less than one hundred and five millions, forty-three thoufand, feven hundred and fifty individuals of the fame kind. It appeared alfo in the courfe of the experiments made upon thefe infects, that the caterpillars which were furprifed by the winter before they had paffed their chryfalis fate, would furvive in the ground till the next fummer if they were not more than three inches below the furface, and the earth was not clofe, compact, and a little hard, in which cafes they would infallibly perish. It appeared alfo that they would live and multiply in oats, as well as in wheat, barley, and rye, in which they were most commonly found, and that the eggs were depofited between the two grains that grow on one pedicle, which is faftened to the ftem that forms part of the ear, and that they would alfo be produced and thrive in Spanish wheat or maize, if maize was in a state to receive the eggs when the butterflies lay, which happily is not the cafe. The reader will now think it happy that a method has at last been difcovered, by which thefe deftroyers of the ftaff of life may be extirpated, and the grain preferved from harvest to feed-time. [For this method fee our article of Projects for this year.] The hiftory of the fly called a Bott, from Mr. De Reaumur, AMONGST the animals that are ufeful to mankind, the horse is certainly entitled to the firft rank; and yet this animal, confiderable as it is, and contrived by its figure and beautiful proportion to afford us pleasure, was not given to mankind alone; there is a fpecies of fly, whofe right in this creature may be looked upon as ftill better founded than our own. If the horse be useful to us, he is abfolutely neceffary to this fly-the fame Being that formed the horie, formed alfo this fly, which depends G 3 pends wholly on the horse for its prefervation and continuance. The flies we are fpeaking of, like thofe of all other fpecies, receive their first life and growth in the form of worms, -but these are worms that can be produced and nourished only in the intestines of a horse. It is there alone they can enjoy the proper temperature of heat, and receive the nourishment neceflary for them. Befides the long, and fometimes very long worms which have been obferved in the bodies of horfes, there have been alfo fhort ones.[By thefe are to be underflood what we call Botts.] All authors, both ancient and modern, who have treated of the diseases of horses, have taken notice of these worms,--but M. Vallifnieri is, I believe, the firft who has traced them to the laft stage of their transformation, and has feen them change into a hairy kind of fly like the drone. The flies from which thefe botts are produced inhabit the country, and do not come near houses, at least not near thofe of great towns; and therefore horfes are never liable to have these worms (i. e. botts) in their bodies; if they have have been kept in the houfe, especially in a town, during the fummer and autumn. It is in the former of these feafons, and perhaps too in the beginning of the latter, that the females of these flies apply themfelves to the anus of horfes, and endeavour to gain admittance, in order there to depofit their eggs, or perhaps their worms. The precife inftant of their entrance will scarce admit of an eyewitnefs, but by the meereft chance; yet M. Vallifnieri fays, that Dr. Gafpari had attained this very uncommon fight.-The doctor (he tells us) was one day looking at his mares in the field, and from being very quiet he observed, that on a fudden they became very reftlefs, and ran about in great agitation, prancing, plunging, and kicking, with violent motions of their tails. He concluded, that thefe extraordinary effects were produced by fome fly buzzing about them, and endeavouring to fettle upon the anus of one of them; but the fly not being able to fucceed, he obferved it to go off with lefs noifc than before, to-wards a mare that was feeding at a distance from the reft; and now the fly taking a more effectual method to obtain its defign, paffed under the tail of the mare, and fo made its way to the anus. Here at firft it occafioned only an itching, by which the inteftine was protruded with an increafed aperture of the anus; the fly taking the advantage of this penetrated further, and fecured itself in the fold of the inteftine;-this effected, it was in a fituation proper for laying its eggs. Soon after this the mare became very violent, running about. prancing, and kicking, and throwing herfelf on the ground; in fhort was not quiet, nor returned to feeding, till after a quarter of an hour. The fly then we fee can find means of depofiting its eggs, or perhaps its worms (i. e. botts) in the fundament of the horfe, which, once effected, it has done all that is neceffary for them. If thefe bott worms are not hatched when first deposited in the horfe, but are then only eggs, it will not be long before it happens, from the nutritive heat they there receive. Thefe bott worms, foon make their way into the intestines of the horfe; they occupy fuch parts of this region, as are to them moft convenient; and fometimes (as we fhall fee presently) they penetrate even to the ftomach:-all the hazard they appear to be expofed to, is that of being carried away from the places they have fixed on by the excrement, which may feem likely to drive all before it.-But nature has provided for all things, and when we fhall have further defcribed these bott worms, it will be seen that they are able to maintain their fituation, and to remain in the body of the horse as long as they pleafe. There is a difference in colour obfervable between thofe that are taken by force from the inteftine of the horse, and thofe which come away of their own accord; fome are greenish, fome yellowish, and others nearly brown; thefe laft are nearest to, and the greenish ones the farthest from the time of their transformation. There is a time when thefe bott worms are of themselves defirous to leave this their habitation, it being no longer convenient to them after the purposes of their growth are anfwered. Their transformation to a fly must be performed out of the horse's body, and accordingly, when the time of their transformation draws near, they approach towards the anus of the horfe, and then leave him of their own accord, or with the excrement, with which they then fuffer themselves to be carried along. If M. Vallifnieri and myself have rightly obferved the pofition of their claws, fome of them differ from each other in this refpe&, but are perfectly fimilar in every other particular, and which change into flies fo nearly alike, that I am convinced, they are of the fame kind and origin. The figure of these bott worms affords at first fight nothing remarkable, but they appear like many other worms of the firft clafs, to which they belong, that change into flies with two wings, and like the greatest part of the worms of that clafs, they are provided with a fort of fcaly claws, with which they draw themfelyes forward. However this be, the bott worms, which are the subject of our prefent pursuit, have two unequal claws; and fince I have been acquainted with the nature and use of them, I have had no difficulty to conceive, how they may ftill remain in the intestines of the horfe, in oppofition to all efforts of the excrement to force them out one of them, that I was handling and examining, fastened upon my finger in fuch a manner, that I found great difficulty to difengage myfelf. Thefe claws are a fort of anchor, differently difpofed from thofe of common anchors, but contrived to produce the fame effect. Befides these two claws, nature has given to each of thefe bott worms a very great number of triangular fpines or briftles, very fufficient to arm them against the coats of the inteftines, and to refift the force employed to drive them towards the anus, provided the head be directed towards the stomach of the horse. It will be asked, no doubt, if in the inteftines of the horfe, that Shefe bott worms are not dange ous to horfes ?-The mares which afforded me, for feveral years, thofe on which I made my obfervations, did not appear to be lefs in health, than thofe which had none;-but it may fometimes happen, that they are in fo great a quantity in the body of the horfe, as to prove fatal to him.- M. Vallifnieri fuppofes thefe bott worms, to have been the caufe of an epidemical difeafe, that deftroyed a great many horfes about Verona and Mantua in the year 1713-the obfervations communicated to him by Dr. Gafpari fufficiently confirm his fuppofition. This gentleman, upon diffecting fome horfes that died of this diftemper, found in their ftomachs a furprifing quantity of short worms, of which, to give us fome idea, he compares them to the kernels of a pomegranate opened each of thefe, by gnawing on the coat of the ftomach, had made for itself a kind of cellule therein-each of these cavities would easily contain a grain of Indian wheat. It is eafy to imagine by this means the ftomach must be reduced to a wretched condition; the outer membranes were inflamed, and the inner ones ulcerated and corrupted; a very small quantity of thefe worms were found in the fmall inteftines, and only a few in the larger, to which laft they were found affixed, but had not corroded them. It is only perhaps when thefe bott worms are in great numbers, and thereby incommode each other they make their way towards the ftomach- - and indeed a very few. flies must be enough to overstock the infide of a horfe, provided, they fhould depofit all their eggs, and fuch fhould all be animated, M.Vallifnieri having counted feven hundred and odd in the body of one fingle fly. When one of these botts has left the anus of the horfe, it falls on the ground, and immediately feeks out for fome place of fafety, where it may retire, to prepare for the laft tage of its transformation, by which it is to become a fly. And now by degrees the skin hardens and thickens, and at length forms a folid fhell or cod, the form of which scarce differs from that of the worm. It is first of a pale red colour which changes into chefnut, and at length, by the addition of gradual and fucceffive fhades of brown, the fhell is rendered black. -as yet The worm or bott before it paffes into a nymph is of the form of an oblong ball; it remains in this form much longer than worms of the flesh-fly kind. I have met with worms, that retained this figure five or fix days one can perceive no traces of the legs, wings, and head of the nymph.Hence I first learned, that these bott worms do not become nymphs immediately upon their first change, but that, in order to become flies, they muft uxdergo one change more than caterpillars ordinarily do to become butterflies. Account Account of a marine production of a very ambiguous nature, from the Philofophical Transactions for the year 1762. IN N the month of June, 1759, the fquadron deftined against Quebec arrived in the river St. Laurence, when being in the latitude 49. 50. north, and about ten leagues to the eastward of Anticofti (an island in the mouth of the river) we founded, and ftruck ground in 42 fathoms; the foundings white fand and black specks, Having, at the fame time, thrown over a fishing-line, the hook was found ftrongly attached at the bottom; and, after fome efforts, brought up a piece of rock into the furface of which was inferted a ftrong tendinous fubftance, of a light brown colour, in length about feven inches; it was round, and nearly of the thickness of a common goofe-quill; the other end formed a fack, or bag, of the fize and fhape of a pigeon's egg. The whole of this fubftance was elaftic; and, upon preffing the bag, I plainly difcovered a contained fubftance, and imagined, that it was attended with motion. Thefe, Sir, are all the particuJars I have got to offer upon this unknown fubject, whether animal, zoophite, or fubmarine plant, I leave to your determination. [Thus far Dr. Nafmyth, who fent this production over to England. The following defcription is by fome learned and ingenious members of the Royal Society, who examined it.] Upon our examination, it appeared to us to come nearest to what has been, by naturalifts, called Priapus; give us leave, therefore, to name it Priapus pendunculo fili.. formi corpore ovato. The body was oval, and in fize between a pigeon and pullet's egg, fmooth, membranous, and of a filver afh colour. What appeared to be the mouth was fituated a little below the apex, and was quadrivalvular, in the form of a (+) crofs. The anus was on the fame fide, a little above the bafe, or infertion of the ftalk, and alfo quadrivalvular. Towards the apertures of the mouth and anus, the body felt more callous. From this body iffued a peduncle, or ftalk, of ten inches in length, the extreme end of which was fixed to a piece of rock. This ftalk was of a light brown colour, about the thickness of a large hen's quill, round, hollow, rough, and of a membranous, leather-like fubftance. When the body was opened, the internal coat appeared to be compofed of reticular fibres. The interior orifice of the mouth was furrounded by a radiated fubftance, about the fize of a filver penny, thicker, and more callous than the coats of any other part. The internal aperture of the anus was compofed of fibres interwoven with one another. From the apex to the bafe on each fide defcended obliquely, and winding, a fmooth folid body, in width about one fifth part of an inch, part of which feparated in the examining. We cannot give a clearer idea of this body, than by faying, that it had greatly the appearance (except in fize) of one of the fmalleft inteftines, and was attached to the interior surface of the main body,, much in the way as they are to the mefentery. Remarks |