But how is the blood enabled to sustain this loss ? Or by what channels are its supplies convey ed into the course of circulation ? We see the food taken into the mouth, masticated by the teeth, and plentifully mixed with the juice called saliva, which flows into the mouth from a great number of neighbouring glands. As it moves along, it receives more juice from vessels and other glands on the passage : it arrives soon at a large dilatation of this canal, called the stomach, where it meets with another juice, named the gastric juice. The canal, as it proceeds from the stomach, becomes narrow and is named intestine : here it has many convolutions, and is nearly six times the length of the body. Into this portion of the canal, likewise, glands and vessels con tinue to pour their fluids, to lubricate the tube, or to as sist in the preparation of aliment. Two of these Iluids are remarkable ; one of a greenish colour and a bitter taste, which is named bile, and is secreted in the liver ; the other, called pancreatic juice, from the large gland in which it is prepared. By the assistance of all these, juices, by the heat of the body, and by the action of the canal, which possesses a degree of muscular power, all the nutritious part of food is converted into a white and thin fluid, resembling milk, which is called chyle. Sup pose now, that the whole nutritious part of the food is converted into this fluid, it is very evident, that it must by some means or other find its way into the blood ; but by what vessels, or by what mode of communication, con tinued for many ages, a mystery in anatomy. An Italian anatomist happening to open a live clog, accidentally dis thus given a very general description of the hu man structure, we shall now retrace the various steps by which the science of anatomy has advanced from its rude origin to its present perfection. 11.2sides the ob vious methods of dissection and observation, this science is indebted for much of its progress to the application or mechanical and chemical philosophy, and to an attentive observation of the causes of those phenomena that characterise living organized systems of matter. in the brief sketch which we pi opose to give of the history of anatomy, we shall attend to each of these sources of in formation,—mark the principal discoveries to N% hich they have led,—and point out those particular departmcnts of the science, to the improvonent of w hich they may stiil be subservient.
The discoveries which have been made by means of dissection and observation, naturally claim our first at tention. Though dissection, as an art, was unknown in the early periods or society, many opportunities would occur of acquiring some knowledge, however general and imperfect, of the animal structure. Even the sa vage could not fail to observe, partially, the organization of the animal which he slew in the chase, and devoured in the feast. Human bones would be seen strewed on the field of battle ; whole skeletoas would sometimes be found of those w ho had perished accidentally, or by violence ; and similar casualties would prc:ient an op portunity of Lontemplating, in the mangled carcass, the soft and internal parts or the human frame. Accordingly the rudest and most ancient languages indicate an ac quaintance with the principal bones, and the most im portant and conspicuous viscera in the human body, though their intimate sti neturc and functions were as •it unknown; by attending to wounds and frac tures, to the progress of disease, and the methods of cure, men WWI id UN CI) acquire sonic knowledge of the animal econon,‘.
Their 'Knowledge, however, was long very imperfect ; and, as they did not practise anatomy as an art, and sel dom reasoned on what they had seen, their observations were almost totally useless, and neither reflected light upon medicine, nor regulated the operations of surgery.
`.ionic, indeed, are extravagant. enough to maintain, that the early Egyptians possessed as accurate and exten sive a knowledge of the human body as the most skilful modern anatomists ; that Athotis, one of their first so vereigns, published several books on anatomy, in which he laid down rules for dissection ; that one of the medi cal treatises of Hermes related to the Structure of the human body ; and that a considerable knowledge of ana tomy was implied in the art of embalming. It is almost unnecessary to advert to these absurd pretensions. The claim of Athotis is indeed supported by Eusebius and Africanus ; but their authority was the tradition of Egyptian priests, who, to exalt their country in the es timation of the credulous Greeks, pretended an intimate acquaintance with every thing connected with literature and science. Hermes was the tutelary spirit of the pillars on which the writings of Egypt were inscribed, and was therefore worshipped, not only as the patron, but the inventor of their arts and sciences ; but, as Hermes in Greece, at Rome, and Thoth in Egypt, signified a pillar as well as a god, by the wri tings of Hermes might either be meant the writings inscribed on the pillars, or the writings of the god to whom these pillars were consecrated. In the last of these meanings, the priests were anxious that the phrase should be understood. We are told, indeed, by Jam blichus and Galen, that every new discovery was first approved by the common voice of the priesthood, and afterwards engraved, without the author's name, upon these pillars, or on stones of the temple. Thus these writings were regarded as the productions of a divinity, and were held in such veneration, that to attempt to alter them in the least degree was considered as an act of unpardonable sacrilege. When a patient died, the surgeon, or physician, who attended him, underwent a strict examination : and if convicted of the slightest from the practice recommended by Hermes, they were condemned to death. From these facts we should be led to entertain no very high opinion of the anatomical knowledge of the Egyptians.
Many, however, have imagined, that great improve ments must have arisen from a custom, peculiar to the Egyptians, which confined the attention of medical practitioners to some particular organ or function, with out permitting them to undertake the cure of the whole system. It cannot be doubted that such a custom would have been extremely beneficial, had it been aided by a general knowledge of the system ; or had it originated in the same views which suggested the modern division of labour. But what improvement could be expected from a practice founded on the gross superstitions of judicial astrology ? Or what shall we think of the science of that people, who divided the human body into thirty six parts, over each of which a tutelary genius presided, whose displeasure, or neglect, was the cause of all dis eases ;—di,eases which were to be removed, not by the aid of art or of medicines, but by symbolical forms, ana magical invocations ? It has been said, that the practice of embalming would familiarize the Egyptians to anatomical inquiries. But, in reality, that practice neither required, nor was calcu lated to impart, any skill in anatomy. It was merely a religious ceremony, performed in the rudest manner ; and could it even have imparted any insight into the animal structure, the detestation and abhorrence in which those who performed the operation were held by their countrymen, would effectually prevent them from communicating the knowledge ' which they had thus acquired. Their mummies exhibit few marks of dex terity or skill. Our modern collections of birds, quad rupeds, fishes, and insects, display incomparably more ingenuity ; and yet these may be easily prepared without any anatomical acquirements.