rations. In the fummer, this wonderful infect is oviparous ;. but in autumn it depofits its eggs on the bark and branches of the trees. Facts of this kind teach us to draw our conclufions. with caution.-Eggs refemble the feeds of plants. Both are invested with a hard cruft. The rudiment of the future plant is concealed under the cicatrice of the feed, resembling the punctum faliens, or living part of the egg. From these points veffels are fent out, in both, to abforb the nourishment. Trees and fhrubs, which produce by means of buds, may be confidered as resembling viviparous animals. In bulbous plants the root is obferved, towards the end of autumn, to contain the plant in miniature. The eyes of potatoes remain torpid during the winter, but burst forth into life by the genial influence of vernal warmth. The water lentil, a small plant which covers ftagnating pools, multiplies by detaching thin films from its leaf. Plants, like animals, have their feafons of production. In northern climates, which enjoy a fhort fummer, the multiplication is rapid. Some animals are capable of engrafting, Befide the polypus, the actinia, or fea-netile, has the fame fingular property. Plants too, like animals, are fubject to disease and decay. By excefs of heat they become languid and fhrivelled. Deprived of light and air, they become fickly and lurid. An unfriendly foil, and a bleak exposure, check their vigour and their growth. Age or accident puts a period to their existence, and the mouldered veftiges fupply matter for the production of new generations,

In Chap. II, Mr. Smellie confiders the organs and structure of animals. He gives a very neat and clear view of the conftruction and economy of the human body; and is thus enabled to inftitute a comparison, and mark the differences which subsist between it and thofe of other animals. The degree of intelligence that is to be found in the brute creation correfponds to the fimilarity of their ftructure to that of man. In quadrupeds the uniformity of plan which runs through them all is wonderful, The variations arife almoft folely from the difference of the proportions between the feveral parts. Immediately under the skin of quadrupeds, there is a thin mufcular fubftance, called parniculus carnofus, by the fudden shrinking of which they are enabled to drive off infects. The carnivorous tribes are furnished with the weapons of destruction, and inherit difpofitions that are unfocial and cruel. Their ftomach is fmall, and their inteftines fhort. Their food runs into putrefcency, and is eafily digefted; and the faces would prove hurtful from their acrid quality, if not fpeedily difcharged, Herbivorous quadrupeds are in general furnished with four ftomachs, and their inteftines are Jong, capacious, and convoluted. Their food is of a less nourifhing quality, of more difficult digeftion, and more tedious

in the converfion into chyle. After maftication the food is thrown into the firft ftomach, and, after concocting for fome time, it is brought up and chewed, and again fent into the fecond; whence it fucceffively paffes into the third and fourth. The external form of the herbivorous animals correfponds to their gentle difpofitions and mode of life. The shortness of their legs, and the length of their neck and head, enable them to pafture. They have no cutting teeth in the upper jaw, and are totally deprived of tufks. They have no claws; and hoofs or horns are their only inftruments of defence. Comparative anatomy informs us that man was not deftined to feed upon vegetable or animal fubftances alone. He can fubfift upon either, but the proper mixture of both is moft conducive to the vigour of the conftitution. In man and the quadrupeds, the circulation of blood in the foetus is not complete. Inftead of flowing through the lungs, it paffes directly, by the foramen ovale, from the right auricle to the left. After birth, when respiration commences, this aperture completely clofes. But, in the amphibious animals, the perforation is always entire, which gives them the power of fufpending the action of the lungs without inconvenience. The feal is remarkably gentle, and can be inftructed to imitate various human actions. His manners are social and affectionate. The young can diftinguish the mother in a numerous troop, and readily obey her call. The elephant has only one stomach, but this defect is fupplied by the extreme length of the inteftines. This noble animal has been diftinguilhed in all ages by his fize, his ftrength, his fagacity, and his fteady affection. His trunk ferves him inftead of hands. He can lift the smallest piece of money from the ground, untie the knots of ropes, and open gates by turning the keys or pushing back the bolts.

Mr. Smellie next proceeds to confider the ftructure of birds. Their external figure is admirably adapted to their mode of life. The wings are articulated with the breast-bone, and are furnished with muscles of remarkable strength. The tail ferves as a rudder to direct their airy courfe. To diminish the refistance of their motion their heads are small, and terminated by long sharp beaks: They are likewife deprived of external ears, and of protuberant nofes. Their tails, inftead of vertebræ, mufcles, and < skin, confift entirely of feathers. They have no pendulous scrotum, no bladder, no flesh uterus. Neither have they an • epiglottis, though many of them poffefs great powers of modulation, and fome of them may be even taught to articulate ⚫ words. To lighten their beaks, they are deprived of lips and teeth; and their abdomen or belly is proportionally small and Their feathers are inferted in fuch a manner as to

narrow.

lie backward from the head, and thus throw off the rain that 'might incommode them, and at the fame time enable them to wing their courfe against the wind.' Birds are continually paffing through bushes and thickets; and Nature, to protect them from receiving injury, has furnished the membranum nictitans, which can be drawn over the eye like a curtain, and while it fhades them from external violence, it admits light fufficient to direct their courfe. Their rump terminates in a large gland, fecreting an oily fubftance, with which they occafionally anoint their feathers, and thus prevent the water from infinuating. Birds are divided into the granivorous and the carnivorous. In the former class the cefophagus or gullet terminates in a membranous fac, called the ingluvies or craw, where the food is macerated and partly diffolved. It then paffes into the ventriculus fuccenturiatus, and, after receiving a farther dilution, it defcends into the gizzard or true ftomach, which confifts of two very strong muscles, covered externally with a tendinous subftance, and lined with a thick, firm membrane. The lungs are red spongy bodies, attached to the back-bone, covered with a pervious membrane, and communicating with large veficles that are spread over the whole abdomen. Thefe veficles render the birds fpecifically lighter, and fupply the place of a diaphragm. In the male the tefticles are proportionably large, and communicate with two feminal ducts that terminate in the penis. In the female the clufter of yolks is analogous to the human ovaria. The yolk paffes into a canal called the infundibulum, where it receives a gelatinous liquor that composes the white. The uterus is a large bag fituated at the end of the infundibulum; and here the egg receives its laft covering, and is pushed out of the vagina at an aperture placed immediately over the anus. This clafs of birds has a ftrong analogy to the herbiborous quadrupeds. Their internal structure is fimilar, and their difpofitions are equally focial and gentle. The birds of prey have the fame number of ftomachs, though smaller and weaker; and, like those of the rapacious quadrupeds, their inteftines are fhorter, and they can endure hunger for a great length of time. They are quick-fighted; and those that feed upon carrion have an exquifite fcent. As in this class the care

of the young is intrufted to the mother, the females are larger, ftronger, and more beautiful, than the males. Their difpofitions are fullen and cruel. They retire to fequeftered rocks, or spend their lives in the folitary gloom of a foreft. The feet of waterfowls are generally furnished with webs, which enable them to fwim. Some feed upon the infects that are found in the mud, and frequent marfhes and the margins of lakes and rivers.

They

They wade in fearch of their prey, and, for this purpose, are furnished with tall naked legs and long necks and bills.

Structure and organs of fishes. Fishes are extremely various in their shape and fize. The organ of fmell is large; and that they poffefs the fenfe of hearing has lately been completely demonftrated. Their ftomach is fmall, and the guts fhort. The swimming bladder is an oblong white membranous bag, contiguous to the backbone, and containing a quantity of air. They have the power of contracting or dilating it at pleafure, and are thus enabled to rife or defcend in the water. In thofe fishes that grovel near the bottom it is wanting. The heart is of a triangular figure, and has only one auricle, one ventricle, and one great artery, diftributed entirely on the gills.

Mr. Smellie proceeds to confider the structure of infects. Here nature sports with variety, and the fubject is uncommonly curious and difficult. Infects have commonly fix legs, but the number is often much greater. Their antenna, or feelers, feem to affift them in groping, and examining the fubftances with which they meet. Their eyes are abfolutely immoveable; but this defect is fupplied by their number. In a few infects thefe are smooth; in others they are hemifpherical, and composed of many thousand diftinct lenfes. It is not certain whether they poffefs the fenfe of hearing, but it feems probable. The bodies of infects confift, in general, of a head, trunk, and abdomen. In fome there are four or fix palpi fixed to the mouth, which affift them in holding their food while eating. The most wonderful part of the hiftory of infects is, the metamorphofes which the winged kind undergo. They iffue from their eggs in the foft and moift ftate of the worm or caterpillar. They are then transformed into the inanimate nymphs or chryfalids, and, after continuing fome time torpid, they feel the influence of the returning heats of fpring or fummer, and burft from their prison in the form of beautiful flies. Mr. Smellie examines the infects according to the arrangement of Linnæus, and selects the more remarkable fpecies. 1. The coleoptera. This order includes the scarabai, or beetle tribe. Thefe live for fome time in the form of caterpillars or grubs, and feed upon roots or putrid matter. After transformation they change totally their habits, and fome, that before feed voraciously upon dung and carrion, are nourished with the pureft nectareous juices, extracted from fruits and flowers. In fome, the period of exaltation is of fhort duration. The ephemeron fly lives three years a grub in the water. It exifts only a day in the winged state, depofits myriads of eggs, and gives place to future generations. 2. Hemiptera. The whole of this order are furnished with a probofcis or trunk for extracting their food. To it are referred

the

the cockroach, the bug, the cricket, &c. The fire fly, a native of the tropical regions, emits a lively light during the night. 3. Lepidoptera. This order includes the butterflies and moths; and the individuals are distinguished for their elegance and beauty. 4. The neuroptera. The wings of this order refemble beautiful network. Their tail has no fting; but the male is frequently furnished with pincers. In the dragon-fly the organs of the male are fituated in the breast, those of the female in the extremity, and, during coition, they have the appearance of a double animal. The fpring-fly frequents ftreams. Its caterpillar is in great request among the fishermen, and known by the name of flone or cod bait. 5. Hymenoptera. In general the infects belonging to this order have four membranaceous and naked wings. In fome of the genera, however, the neuters, and in others the males, or even the females, have no wings. Their tails, except in the male fex, are • armed with a fting.' To this order are referred the ant, the bee, the wafp, &c. 6. Diptera. This, order confifts of twowinged infects. The caterpillars of the gad-fy lie concealed in the fkins of cattle, where they are nourished during the whole winter. This order includes alfo the common fly, the gnat, and the horse-fly. 7. Aptera. This order is compofed of those infects that are not furnished with wings. It includes the loufe, the flea, the spider, the fcorpion, &c. The laft order is that of the vermes, or worms. The hairworm is common in our fresh waters, and, in this country, is perfectly harmless; but in Africa and both the Indies it is extremely noxious. It infinuates itself into the naked feet or limbs of children and unwary perfons, and produces a dangerous inflammation. The earth-worm is hermaphrodite. It feems to feed folely upon fine earth. The cuttle fish is, in many refpects, a fingular animal. The Medufa has the appearance of a lifelefs mafs of jelly floating on the furface of the ocean; but, though the fport of the waves, it is ftill a gregarious animal.

Chap. III. treats of refpiration. Upon this fubject Mr. Smellie gives a view of the doctrines contained in Dr. Crawford's ingenious treatife on animal heat. It is found that air, which has affifted in refpiration, has its capacity for heat diminished. Hence the principal fource of vital warmth. The blood absorbs the oxygenous part of the air; but whether it also evolves carbone is not yet decided. There is a remarkable circumftance in the ftructure of birds. The lungs communicate with air cells that are difperfed over the whole body. The ufe of this arrangement is not yet well afcertained. Some have imagined that the purpose of it was to expand the volume, and thus facilitate the afcent of the bird. Mr. John Hunter fuppofes,