This work is in the main a continuation of the volume entitled “The Growth of Medicine,” but it is also intended to serve as an amplification of the latter part of that work, which, owing to various circumstances that were in large measure beyond my control, lacked completeness. The most troublesome of these adverse circumstances was the fact that I had failed, during a recent visit to Europe, to find those sources of trustworthy information upon which alone such a narrative could properly be based; and later still, when I made my first attempts to construct the text of the present volume, I again encountered the same kind of obstacles, but in an even greater degree, and was then strongly disposed to abandon the undertaking altogether. At this juncture of affairs, however, I was much surprised and pleased to receive from Mrs. Charles F. Norton, the librarian of Transylvania College at Lexington, Ky., a letter in which she stated that the college had in its possession a large collection of medical works which had been purchased at Paris, France, in 1819, at which period of its history the institution bore the title of Transylvania University and possessed a flourishing medical department; and that the president of the institution would be happy to extend to me every possible facility for utilizing this great mass of historical material. Shortly afterwards, in reply to my request that I might be furnished with a partial list of the books contained in this collection, in order that I might determine how many of them related to the period in the history of French medicine in which I was at that time particularly interested,—the period, mainly, from about 1760 to 1830,—I received a card catalogue of the titles of over 100 French, English and Latin treatises. This information removed all doubts from my mind concerning the wisdom of my visiting Lexington, and I accordingly signified my prompt acceptance of the cordial invitations extended to me by President Crossfield. As I write these lines I am prompted to add the further statement that during my stay at Lexington, which covered a period of seven months, I received every assistance from the Transylvania College authorities that I could possibly desire; and in particular I wish to express my deep sense of gratitude to the librarian, Mrs. Norton, for the interest which she manifested in my work and for the valuable assistance which she rendered in hastening its completion.