Again, without the aid of comparative anatomy, we might often be induced to entertain false conceptions of the relative importance of different organs : but when we see these organs imperfect in one animal ; diseased, obliterated, or extracted in another ; or naturally want ing in a third, without any essential injury to life ; we have then the criteria by which we may be able to form some judgment of that rank which these organs hold even in the human species.
Thirdly, comparative anatomy becomes necessary in ascertaining the action of organs. All the functions have ceased long before the human body can be opened, and it is only in the inferior animals that we can presume to make experiments examining the movements of the different organs, before the principle of life has escaped. It is chiefly in this field of enquiry that we have obtained the correct knowledge which we now possess, of many of the animal functions.
To the naturalist, comparative anatomy affords one of the surest guides by which he can direct his steps. With out an acquaintance with the internal structure, as well as with the external forms of animals, our knowledge of zoology must be incomplete and inacurate.
Indeed, anatomy and zoology mutually illustrate each other. In our examination of zoological works, anato my comes forward to our assistance like a friendly interpreter, explains terms which we should not other wise understand, and phenomena which we could not comprehend. It presents before us a wide creation of animated beings, infinitely varied in form, magnitude, and colour ; in strength, instinct, habits, and manners ; yet all exhibiting many of the same common organs and functions, thus proving, that our generic and specific differences are only varieties of the same plan ; that we ought to study the whole of animated nature, if we de sire to have enlarged or just ideas of the animal economy.
Before the anatomy of inferior animals was so much cultivated as it has lately been, our zoological classifica tions were extremely imperfect ; and even that of the justly celebrated Untie, is now acknowledged to be much less accurate than it might have appeared, had its author been more conversant with anatomy. We shall immediately see how much the classification of animals has been improved by the labours of the anatomical na turalists of the present day.
To offer any historical view of the origin and progress of comparative anatomy, would be, in a great measure, to repeat what has been already given in our general history of the science, since many of those whose names are most celebrated as the improvers of human anatomy, were also famous for their attention to that of other Of these it is sufficient for us to notice Demo Herophilus, Erasistratus, and Galen, ancients ; and Eustachius, Fallopius, Fabri , fn, y, De Graaf, Redi, Willis, Ruysch, ? , he two Monros, John Hunter, Vicq. d'Azyr, tilunfenbach, Cuvier, Dumeril, and La Marek, among the moderns. Of those who paid most attention to com parative anatomy, and were not remarkable for their writings on that of the human body, we may mention Aldrovandi, Rondelet, Bellonius, Swammerdam, Blasius, Tyson, Reaumur, Daubenton, Trembley and Bonnet.
There are few complete or systematic works on com parative anatomy. The best with which we are ac quainted among the earlier writers are two works of Blasius, one in 4to, entitled Anatomic Animalium Figuris Variis Blustrata, published in 1681, the other a smaller work, entitled ?natome Hominis Brutorum ryue Variorum, published in 1673 ; the system of anatomy of Collins, and the anatomical works of Valentin/. There is a cem pendium of comparative anatomy by the first Monro, which, considering the period of its publication, is well deserving the attention of our readers. Within these few years have been published two systems of compara tive anatomy, which have justly superseded all other ge neral works on this subject. One of these is the Le' d'Anatomie Comparee of Cuvier, in 5 vols. 8vo.
the first two were published in 1800, edited and have been translated into English under the direction of Mr Macartney. The last three were published in 1805, and were digested Duvernoy, under the imme diate direction of the author. The other systematic work to which we allude is the system of comparative anatomy by Blumenbach, published originally in German, and lately translated into English by Mr William Lawrence.