Straits, a circumstance rather to be wondered at, as the voy. age must necessarily be less hazardous than that to Lancaster Sound, since, according to Captain Parry, Fox Channel at the head of the Straits is not only free from ice during summer, but swarming with whales, unconscious of danger. This is certainly a rich field for future adventure. The entrance to the Straits is for the most part inaccessible till August, being hampered with icebergs driven about by the waves of the ocean; these become less numerous, and more insignificant, with the progress to the westward, until they entirely disappear, when the chief obstruction lies in the floe ice, which had been formed in winter, then in a state of rapid solution.

LEITH, Nov. 30. 1830.

Observations on the History and Progress of Comparative Anatomy. By DAVID CRAIGIE, M.D. &c. Communicated by the Author *.

Few sciences have undergone greater vicissitudes in their proEW gressive advancement, than that of comparative or animal anatomy. Originating at an earlier period than that of the human frame, and cultivated as a substitute for it, both by the ancients and also by some of the moderns, it fell under the contempt and degradation which all misapplied departments of knowledge are destined to incur. When at length prejudice began to subside, and reflection taught anatomists that the knowledge of the struc ture of the lower animals, if kept in its proper place, and made subsidiary to, but not substituted for, that of the human body, may be not only free from harm, but productive of the greatest benefits, it began to attract the attention of physiologists, and to assume something like a definite rank among the natural sciences.

It may be observed, nevertheless, that on this subject a considerable degree of misconception prevails, both generally, and also amongst those whose pursuits require some knowledge of

* Dr Craigie is author of Elements of General and Pathological Anatomy, 1827; joint Editor of the Edinburgh Medical and Surgical Journal, and conductor of the Anatomical department of the Encyclopædia Britannica.-Edit.

the structure of the human frame. Whatever be the cause, it requires little penetration to perceive, that, with the exception of those eminent and intelligent persons who have devoted their lives almost to the cultivation of this branch of natural knowledge, very indistinct and inaccurate notions of the nature and objects of comparative anatomy are entertained. Regarded as an appendage to human anatomy, or as the occasional source of comparative illustrations, animal anatomy has been appealed to chiefly when it promised to explain obscure and anomalous points in the structure of the human body; and its cultivation has consequently been too exclusively confined to those who were known as mere human anatomists.

That this is a sufficiently legitimate application of the lights of comparative anatomy, I do not deny. But while it is defective in giving a very limited view of the nature and objects of the science, it has had the bad effect of giving currency to the opinion, that comparative anatomy is merely a subordinate department of human knowledge, occupying only an inferior rank in the scale of natural science. The very name also by which it has been distinguished, has contributed in no ordinary degree to convey an erroneous impression of its objects. Though one of the principal objects of all human inquiry is, in one sense, comparison of different objects, and the formation of general conclusions from these comparisons; yet, so long as the structure of animal bodies is studied merely in reference to the standard or type, furnished by the organs of the human frame, it may be safely asserted, that it can derive neither advantage nor illus tration from the general principles of philosophical research. Animal anatomy, or zootomy, as it may be more justly denominated, instead of being regarded as a subordinate appendage of human anatomy, is itself a comprehensive science, embracing the knowledge of all the varieties of structure exhibited by the classes, orders, and tribes of the animal world, and of which that also of the human subject forms only a constituent part. The latter, indeed, has justly acquired pre-eminent interest, from its connexion with the art of preserving life and healing disease. But these circumstances cannot give it, as a branch of science, a rank higher than that of the organic constitution of animal bodies generally, or erect the structure of the human frame into

a general standard of reference; and while the importance of correct knowledge of the latter is readily admitted, that of the animal tribes generally is not less valuable, in reference to the great purpose of illustrating the nature and characters of animal structure and living actions.

The soundness of these principles it would be easy to illustrate and enforce, in different modes. But perhaps by no method can they be placed in so clear a point of view as by the history of the science itself, and of the successive stages through which it has passed. In this manner we shall be enabled to appreciate the estimation in which it has at different periods been held, to understand the objects with which it has been cultivated, to distinguish the impediments by which its progress has at different periods been obstructed, and to form a just idea of its utility and applications when cultivated, without reference to temporary, local, or particular purposes, and on the general principles of philosophical inquiry.

SECT. I.-Aristotle and Ancients.

The first person who can be said to have cultivated comparative anatomy systematically, and in a scientific manner, is Aristotle; and it is an interesting circumstance in the history of science, that the same individual who distinguished himself by. the depth and accuracy of his views on the political constitution of society, and the acuteness of his analytical powers in investigating the history of the human mind, and applying it to morals and literature, was also the first to explain the structure of animal bodies. It is further important to remark, that it was to the peculiar construction of his mental faculties, and his turn for generalization, that the success and the failures of the philosopher of Stagira may be traced in both these opposite departments of science; and while most of his political and metaphysical opinions are erroneous, in being founded on too limited a series of observations, the results of his zootomical researches, in which he was less likely to be misled by mere speculation, constitute a collection of facts, of which the value has been recognised by the most distinguished modern anatomists. Aristotle is almost a solitary example of an individual, who, finding

the natural sciences in general, and zoology and zootomy in. particular, quite in their infancy, collected by personal observation a great number of facts, classified them in systematic order, and derived from them useful general conclusions; and while to these efforts comparative anatomy may be said to have owed its existence entirely, he further rendered the substantial service of being the first to apply its facts to the elucidation and distinctions of zoology. Generalization, indeed, distinction and classification, were the predominant features of the mind of the Stagirite; and while to these objects all his individual observations were directed, they appear to have afforded the principal incentive to diligence in observing and collecting. The works of this ardent naturalist shew that his zootomical knowledge was extensive and often accurate; and from several of his descriptions, it is impossible to doubt that his information was derived from personal dissection.

Aristotle, who was born at Stagira, in the first year of the 99th Olympiad, or 884 years before the Christian era, was, at the age of 39, requested by Philip of Macedon to undertake the education of his son Alexander; and during this period he is believed to have composed several works on anatomy which are now lost. The military expedition of his royal pupil into Asia, by laying open the forests and wilds of that vast and little known continent, furnished Aristotle with the means of extending his knowledge of the history and structure of the animal tribes, and of communicating to the world more accurate and distinct notions than were yet accessible. A sum of 800 talents, and the concurrent aid of numerous intelligent assistants in Greece and Asia, were intended to facilitate his researches in composing a system of zoological knowledge; but it has been, observed, that the number of instances in which he was thus compelled to trust to the testimony of others, led him to commit errors in description, which personal observation might have enabled him to avoid.

The three first books of the History of Animals (Пg Zwar 'Iorogas), a treatise consisting of ten books, and the four books. on the Parts of Animals (Пg Zwwv Mogia), constitute the principal memorials of the Aristotelian Anatomy. From these we find, that Aristotle had already recognised the distinctions of animals into viviparous (woroxa), oviparous (woroxa), and ver

miparous (oxannotona). Of the viviparous, he adduces as examples, man, the horse, the sea-cow (wxn), and those covered by hair; and among marine animals, the cetaceous, as the dolphin and the cartilaginous fishes (~λax), and of these he afterwards states that some are oviparous.

In some interesting observations in the beginning of the second book, on the common characters of animals, and on those proper to certain tribes and genera, he distinguishes accurately the five toes of the elephant; the great strength, mobility, and flexibility of the trunk; the peculiar power of stooping on the hind legs; and the small quantity of shag on his hide. He distinguishes also the Bactrian from the Arabian camel, by the two protuberances, and mentions the single-hoofed hogs of Illyria and Paeonia, a peculiarity which was afterwards observed by Linnæus in those of Sweden. The lower extremities of the human subject, he observes, are distinguished by the disposition of the muscles, which render the hips, thighs and legs much more fleshy in comparison than in quadrupeds; and in man alone, he remarks, is the foot muscular. In speaking of the teeth, he observed, that horned animals are void of incisors in the upper jaw, a character connected with the manner of life and the kind of food. He corrected the erroneous statements of Polybus, Syennesis, and Diogenes, regarding the bloodvessels, which they asserted to proceed from the head and brain, and of others who contended they issued from the liver, but which he demonstrated arose from the heart. His déscription of this organ contains a singular mixture of truth and error. While he accurately distinguishes the site and position of the human heart from that of quadrupeds, as inclined obliquely to the left side of the chest, he represents it to contain three chambers (xμ Teus xiis), a large one on the right connected with the large vein (μevan QBs), the vena cava, a small one on the left, and one of middle size in the middle, connected with the aorta; while he states also, that these chambers are pervious towards the lung, by specifying canals (ano HS nagdias Togo) proceeding from the heart to the lung, which accompany the ramifications of the wind-pipe (agrngia), he shews that he knew the pulmonary artery, and perhaps the pulmonary veins. It is further remarkable, that though he repeatedly represents the heart as the origin of the bloodvessels, as full of blood, and