(for our theorists, having eternity to dispose of, are never sparing in time,) acquire wings. The fame tendency to loco-motion in an aquatic animal, or rather in an animated lump which might happen to be furrounded by water, would end in the production of fins: in a living fubftance, confined to the folid earth, would put out legs and feet; or, if it took a different turn, would break the body into ringlets, and conclude by crawling upon the ground. Although I have introduced the mention of this theory into this place, I am unwilling to give to it the name of an atheiftic scheme, for two reasons; first, because, so far as I am able to understand it, the original propenfities and the numberless varieties of them (fo different, in this respect, from the laws of mechanical nature, which are few and simple) are, in the plan itself, attributed to the ordination and appointment of an intelligent and designing Creator: fecondly, because, likewise, that large poftulatum, which is all along affumed and prefuppofed, the faculty in living bodies of producing other bodies organized like themfelves, feems to be referred to the fame cause; at leaft is not attempted to be accounted for by any other. In one important refpect, how ever, the theory before us coincides with atheiftic systems, viz. in that, in the formation of plants and animals, in the ftructure and use of their parts, it does away final caufes. Inftead of the parts of a plant or animal, or the particular structure of the parts, having been intended for the action or the ufe to which we fee them applied, according to this theory they have themselves grown out of that action, fprung from that ufe. The theory therefore difpenses with that which we infift upon, the neceffity, in each particular cafe, of an intelligent, defigning, mind, for the contriving and determining of the forms which organized bodies bear. Give our philofopher these appetencies; give him a portion of living irritable matter (a nerve, or the clipping of a nerve,) to work upon; give alfo to his incipient or progreffive forms, the power, in every stage of their alteration, of propagating-their like; and, if he is to be believed, he could replenish the world with all the vegetable and animal ductions which we at prefent fee in it. pro The scheme under confideration is open to the fame objection with other conjectures of a fimilar tendency, viz. a total defect of evidence. No changes, like those which the theory 2 H theory requires, have ever been obferved. All the changes in Ovid's Metamorphofes might have been effected by these appetencies, if the theory were true; yet not an example, nor the pretence of an example, is offered, of a fingle change being known to have taken place. Nor is the order of generation obedient to the principle upon which this theory is built. The mamma* of the male have not vanished by inufitation; nec curtorum, per multa facula, Judæorum propagini deeft præputium. It is eafy to fay, and it has been faid, that the alterative process is too flow to be perceived; that it has been carried on through tracts of immeasurable time; and that the present order of things is the result of a gradation, of which no human record can trace the fteps. It is easy to say this; and yet it is ftill true, that the hypothefis remains deftitute of evidence. The analogies which have been alledged are of the following kind. The bunch of a camel, * I confess myself totally at a loss to guess at the reason, either final or efficient, for this part of the animal frame, unless there be fome foundation for an opinion, of which I draw the hint from a paper of Mr. Everard Home's, (Phil. Tranfac. 1799, p. 2.) viz. that the mamme of the foetus may be formed before the fex is determined. is faid to be no other than the effect of carrying burthens; a service in which the species has been employed from the most antient times of the world. The first race, by the daily loading of the back, would probably find a fmall grumous tumour to be formed in the flesh of that part. The next progeny would bring this tumour into the world with them. The life, to which they were destined, would increase it. The caufe, which first generated the tubercle, being continued, it would go on, through every fucceffion, to augment its fize, till it attained the form and the bulk under which it now appears. This may ferve for one inftance: another, and that alfo of the passive sort, is taken from certain species of birds. Birds of the crane kind, as the crane itself, the heron, bittern, ftork, have, in general, their thighs bare of feathers. This privation is accounted for from the habit of wading in water, and from the effect of that element to check the growth of feathers upon these parts in confequence of which, the health and vegetation of the feathers declined through each generation of the animal: the tender down, expofed to cold and wetness, became weak, and thin, and rare, till the deterioration 2 H 2 terioration ended in the refult which we fee, of abfolute nakednefs. I will mention a third inftance because it is drawn from an active habit, as the two laft were from paffive habits; and that is the pouch of the pelican. The description, which naturalifts give of this organ, is as follows: " From the lower edges of the under chap, hangs a bag, reaching from the whole length of the bill to the neck, which is faid to be capable of containing fifteen quarts of water. This bag the bird has a power of wrinkling up into the hollow of the under chap. When the bag is empty it is not seen : but when the bird has fifhed with fuccefs, it is incredible to what an extent it is often dilated. The first thing the pelican does in fishing, is to fill the bag; and then it returns to digeft its burthen at leifure. The bird preys upon the large fishes, and hides them by dozens in its pouch. When the bill is opened to its wideft extent, a perfon may run his head into the bird's mouth; and conceal it in this monstrous pouch, thus adapted for very fingular purposes *." Now this extraordinary conformation, is nothing more, fay our phi *Goldsmith, vol. vi. p. 52.. lofophers, |