Vesalius published, at the age of 25, his grand work on the structure oldie human body, with numerous elegant figures, sup posed to have been drawn by the celebra ted Titian. This work contains such a mass of new information,that it may justly be considered as forming an xra in the history of anatomy We cannot help being surprised that so young a man could have investigated the subject so deeply, at a time when dissection was esteemed sacri legious, and was therefore carried on se cretly, with great danger and difficulty. The great reputation of Vesalius procured for him the esteem and confidence of Charles V. who made him his physician, and kept him about his person in all his expeditions. I lis zeal for science proved the cause of his death : for having opened a person too soon, the heart was seen to palpitate. He was condemned to perform a pilgrimage to Jerusalem ; and as he was returning to take the place of anatomical professor at Venice, he was shipwrecked on the island of Zante, and perished of hunger. It would be nn just to pass over unnoticed the names of Fallopius and of Eustachins, who were contemporary with Vesalius, and contributed greatly to the advancement of anatomy. The anatomical plates drawn and engraved by the latter are executed with an accuracy which can not fail to excite surprise, even in an ana tomist of the present day.
From the time of Vesalius, the study of anatomy gradually diffused itself over Eu rope ; insomuch, that for the last hundred and fifty years it has been daily improving by the labour professed anatomists in almost every country of Europe.
in the year 1628, our immortal country man, Harvey, published his discovery of t he circulation of the blood. It was by far the most important step that has been made in the knowledge of animal bodies in any age. it not only reflected useful lights upon what had been already found out in anatomy, but also pointed out the means of furth er investigation; and accord. ingly we see that, from Harvey to the pre sent time, anatomy has been so much im proved, that we may reasonably question if the ancients have been further outdone by the moderns in any other branch of knowledge. From one day to another there has been a constant succession of discoveries, relating either to the structure or functions of our body ; and new anato mical processes, both of investigation and demonstration, have been daily invented. Many parts of the body, which were not known in Harvey's time, have since then been brought° light ; and of those which were known, the internal composition and functions remained unexplained ; and in deed must have remained inexplicable, without the knowledge of the circulation.
The principal facts relating to this sub ject were khown before the time of Har vey : it remained for him to reject thespe ci oils conjectures then maintained con cerning the blood's motion, and to examine the truth of those facts which were then known, and by experiments to discover those which remained to detected.
This he did, and thereby rendered his name immortal, It seems proper in this place to review the several steps which were made in the investigation of this important subject. Hippocrates believed that all the vessels communicated with each other, and that the blood underwent a kind of flux and re. flux from and to the heart, like the ebbing and flowing of the sea. The anatomists at A lexandria adopted a wrong but ingenious opinion ; as they lomat the arteries empty, and the veins containing blood, in their dissections, they imagined that the former were tubes for the distribution of air, and gave them that name, which they have re tained ever since ; and that the veins were the only channels for the blood. Galen ascertained that the blood flowed both by the arteries and veins,though he knew not then its natural course. On the revival of anatomy in Europe,the pulmonary circula• Bon was known to many eminent men. This was certainly the case NV ith Servetus, who fell a sacrifice, on account of his reli gious opinions, to the savage bigotry and intolerance of Calvin. Fabricius ab Aqua pendente, the preceptor of our famous Harvey, particularly described the valves of the veins, the mechanism of which would absolutely prevent the blood from flowing in those vessels towards ex tremities. When Harvey returned from his studies in Italy, his attention being ex cited to the subject, he began those expe riments, by which he learned and demon strated the fact of the circulation. I lar vey's first proposition of the subject im presses conviction so strongly on the mind that we are left in perfect astonishment, how a circumstance so luminously evident should have remained so long unobserved. It must be granted, that tlic heart projects about two ounces of blood into the arte ries at every pulse ; what then, it may be asked, becomes of this large quantity of blood, unless it circulates ? It must be granted that the heart receives that quan tity prior to every pulse. From whence is it received, unless the blood circulates Harvey tied an artery, and the correspond ing vein received no blood; he tied a vein, and all its branches, and those of the cos. responding artery were choaked with blood, even to the entire obstruction of circulation and motion. But Harvey was not acquainted with the direct communi cation that exists between these vessels. He imagined that the blood transuded front the arteries into the veins through a spongy substance. Much yet remained to by ascertaiaed by microscopical observa tions, and subtile anatomical injections and dissections.