struments, and organization the agent? But a little further, he observes," organization is the instrument, vital properties the acting power" How are we to reconcile the two opinions? Again," the particles which make up a living body," we are told, are dependent on each other; they are all subject to the influence of a cause which animates them. This cause makes them all concur in the production of a common purpose," &c. Afterwards we are informed, " vital properties are the causes of vital functions, in the same way as chemical affinity is the cause of the combinations and decompositions exercised among the component particles of bodies," &c. In the first quotation it will be perceived, that Mr Lawrence maintains the doctrine of Hunter, though he chuses not to give his animating cause the name of "living principle," in the last, that of Bichat, and we have causes termed " vital forces." If the lecturer erred in considering electricity and magnetism as similar, Mr Lawrence is not without fault in the following passage: "The matter that surrounds us is divided into two great classes, living and dead; the latter is governed by physical laws, such as attraction, gravitation, chemical affinity." Attraction, gravitation, and chemical affinity, I always understood, were principles or powers, not laws; but which acted according to their respective laws. To call attraction, gravitation, &c. laws, therefore, is to speak incorrectly. "Would any length of contemplation," Mr Law. rence asks, "have led you to discover that medullary substance is capable of sensation and of thought?" Certainly not; neither would any length of observation, I believe. For, were it possible to view the medullary portion of the living brain, we should not be authorized in regarding its agitations or motions as constituting actual sensation or thought. What! perception, thought, and volition, imagination, and memory, and reason, an arrangement and play of a set of atoms!! Mr Lawrence talks of an "array of philosophical deduction;" but has he not himself been somewhat guilty of a parade of Germanic reference? Of the tendency of Mr Lawrence's philosophy and that of the lecturer, I shall say nothing; I shall only observe, that that philosophy should be received with caution, whose principles are unfriendly to the best interests of mankind.

August 24, 1816.

PART II.

CRITICAL ANALYSIS.

I.

An Introduction to Comparative Anatomy and Physiology; being Two Introductory Lectures delivered at the Royal College of Surgeons, on the 21st and 25th of March 1816. By WILLIAM LAWRENCE, F. R. S. Professor of Anatomy and Surgery to the, College; Assistant-Surgeon to St Bartholomew's Hospitar; Surgeon to Bethlehem and Bridewell Hospitals; and to the London Infirmary for Diseases of the Eye. 8vo. pp. 179. Callow, London, 1816.

We have much pleasure in embracing the earliest opportunity of introducing these eloquent and scientific lectures to the notice of our readers, who, we doubt not, will derive the same instruction and gratification from the perusal, which we have obtained. They were not composed, it appears, with a view to publication, but have been now printed in consequence of repeated applications to the author for copies of them. has added, however, numerous notes and references, which greatly enhance the value of the lectures; in as much as they constitute an ample catalogue of all the best sources of informa tion on the subjects here discussed.

He

The first lecture, which comprehends the "Objects and History of Comparative Anatomy," is rendered particularly valuable by this great store of reference to all the successive discoveries, and to the details of particular facts, which have been presented to the public in various countries and languages. It opens with a warm eulogium on the author's colleague and early preceptor, Mr Abernethy, and with an apology for the imperfections of

the course, from the short time for preparation, which had been allowed him, and then proceeds to state the value and objects of comparative anatomy. He observes, that the first step in the study of life, or the science of physiology, is to examine the organs which are the instruments of life; but that it is absolutely necessary to extend this examination beyond the structure of man or any one animal, to view them under all their modifications and combinations, in order to ascertain what is essential in each.

"The connection and mutual influences of the various organs oppose great and insuperable obstacles to our knowledge of the precise effect and importance of each. Here comparative anatomy comes to our aid: we find in the various classes of animals almost every possible combination of organs, and there is no organ which is not wanting in some class or other. The effect of such combinations and privations cannot but illustrate the nature and operations of the part in question. Fishes have no tympanum, nor external ear; insects no circulating system; many of the lower orders no brain nor nervous system." p. 10.

The author then remarks, that, if we confine our investigations to man, or the more complicated animals, we should be led to the most erroneous conclusions respecting the nature of vitality. A slight injury of the brain will destroy a man or a mammiferous quadruped; while the removal of the whole cranial contents is by no means suddenly fatal in the frog, turtle, and other reptiles. A torsoise lived six months after the skull was opened, and the whole brain removed by Redi. Frogs and newts lived three, four, and five days, after being deprived of their brain by Spallanzani, and leapt, ran, swam, &c. after their hearts were cut out, and lived forty-eight hours. The contrast in the state of vitality in the lower and more simple animals, with that of man and animals of more complicated structure, where the various organs are connected by numerous sympathies, is remarkably illustrated in the reproductive powers of the former, by which fost and mutilated parts are restored. In man and the animals nearly allied to him these powers, though limited, are considerable; as the union of bones and muscles divided by accident, and the restoration of their functions demonstrate; but in the lower order of animals there are scarcely any bounds to this reproductive power,

"The lower we descend in the scale of beings, the more surprising are the manifestations of this reproductive faculty. The large claws of the crab and lobster, aud the entire limbs or tail of the newt, can be restored: the same holds good of the rays of the star-fish and

the arms or tentacula of the cuttle-fish. The entire eye of the newt, with all its coats and humours, has been extirpated, and in the course of ten months succeeded by a new and perfect eye-ball. The whole head of the common snail, with its four horns, has been reproduced after being removed in experiments in many instances. If the earthworm or actinia (the sea anemone) be cut in two, each half will become a perfect animal. The fresh water polype may even be cut into several pieces, cach of which will become a perfect polype." p. 19.

Comparative anatomy, however, has not only illustrated general physiology, but has thrown much light even on the functions of the human frame. The formation of the germ in the ovary, and its passage through the Fallopian tube into the uterus, could not have been discovered in the human subject. The nature and uses of the gall-bladder and of the secretion of bile, has been much elucidated by the anatomy of animals.

The importance of comparative anatomy, in reference to natural history, is also very manifest. For there is a close correspondence between the structure and the habits of animals, which mutually illustrate each other. Some striking exemplifications of this subject are quoted in a note from a valuable work of Cuvier. Every organized being, he remarks, consists of parts which correspond mutually. No one part can change, without the others being modified; and, consequently, each taken separately indicates all the others.

"Thus, if the intestines of an animal are adapted by their organization to digest flesh, and that in a recent state, the jaws must be constructed for devouring prey; the claws for seizing and tearing it; the teeth for lacerating and dividing its flesh; the whole apparatus of moving powers for pursuing and overtaking it; the organs of sense for perceiving it at a distance. Nature must, moreover, implant in the brain an impulse or instinct, leading such a creature to conceal itself and lay in wait for its victims. Such are the general conditions of the carnivorous regimen: every flesh-devouring animal necessarily unites them; for its species could not otherwise subsist. But besides these general conditions, there are subordinate ones, relating to the size, the species, and the abode of the prey and each of these secondary conditions gives rise to differences of detail in the forms which result from the general laws. Hence not only the class, but the order, the genus, and even the species, are expressed in the form of each part."

We have not room to follow out this illustration into all the minutiæ, which are here detailed. The author states, that the succeeding lectures would be a continued illustration of this point: for "no branch of natural knowledge is more interesting than a contemplation of the infinitely diversified organic ar

rangements, by which animals are adapted to their respective places in the creation."

Having thus demonstrated the importance of the study of comparative anatomy, to the natural historian as the only just ground of classification; to the physiologist as the great source of his knowledge of the functions of life; to the physician and surgeon, who can only build their science upon the basis of physiology; and to the natural theologian, who discovers in these striking modifications of structure, in constant relation to the wants, habits, powers, and situations of animals, the strongest evidence of final purposes; he then proceeds to an able historical detail of the discoveries and works of the distinguished writers on the subject, from Aristotle to the present time. We cannot follow him, in the compass of a review, through this complete and interesting sketch of the progress of the science. He speaks with great praise of the immortal work of Aristotle, who not only knew and dissected a great number of species of animals, "but he studied and described them on a vast and luminous plan, to which none of his successors has approached, ranging the facts, not according to the species, but according to the organs and functions-the only means of arriving at comparative results." p. 33. He made the same grand division of animals which has lately been proposed by the French naturalists, only he incorrectly drew the character from the presence or absence of blood, which Lamarck has drawn from the possession or want of the vertebral column. The author regrets that the Romans had not an Aristotle, since that wonderful people had facilities of studying zoology, which have never since existed.

"The largest and rarest animals, brought from all parts of the empire, were exhibited in the triumphs, the public games, and the theatres, to amuse the inhabitants of the imperial city. They saw the hippopotamus, the two-horned rhinoceros, and the camelopard, which have not been brought alive into Europe since. Commodus exhibited five hippopotami at one time; and ten camelopards were shewn by Gordian III. Other foreign and remarkable animals were quite common, as the lion, elephant, panther, &c. Augustus shewed twenty-five living crocodiles at once." p. 36.

After tracing the progress of discovery in Italy, the author comes to the results of the establishment of the Royal Society in this country, and the Royal Academy of Sciences at Paris, referring also to the memoirs and collection of the other foreign institutions, and to the writings of distinguished individuals, who have contributed to the advancement of comparative anatomy; of all which he has given an ample and learned detail,