xl INTRODUCTION. 



the older observers, so vaguely discussed by Haller, 1 so ably 

 used in the masterly memoir of Petit ; and some of the opinions 

 set forth by Quesnay and Senac, partook of that general cru- 

 dity which proved how necessary it was that the properties of 

 the blood should be studied anew by the experimental method. 

 The merit of clearly apprehending the importance of such an 

 inquiry and of supplying an outline of it, justly belongs, I believe, 

 to Richard Davies. His ' Essay/ considered as a demonstration of 

 the distinctive characters of the three proximate principles of the 

 blood, is admirably decisive. Yet it seems to have fallen dead- 

 born from the press, and his labours have been hitherto left to 

 oblivion. Why he has suffered this injustice it might be vain 

 or painful to inquire. There is no reason to believe that he 

 derived his knowledge from Dr. William Hunter ; on the con- 

 trary, this distinguished anatomist may rather have gained his 

 knowledge of the blood from Davies. There is a copy of his 

 ' Essay' in Dr. Hunter's library at Glasgow. It appears pro- 

 bable, from what has already been shown, that Dr. Hunter did 

 not entertain his opinions before the end of the year 1759; his 

 denial of the fibrous structure of fibrin would lead us to sup- 

 pose that he had not then studied it very carefully, and we are 

 not sure that he ever did experimentally. Now it is certain that 

 Dr. Davies had made experiments on the blood at least as early 

 as 1 748, because he gave the results of his own observations on 

 the comparative weights of the serum, buffy coat, and crassa- 

 men, in his ( Tables of Specific Gravities,' communicated to the 

 Royal Society by its then president, Martin Folkes, and pub- 

 lished in the ' Philosophical Transactions' of that year. Davies 

 there mentions the buff as f( sanguinis humani cuticula alba," 

 whence it might be imagined that he had not then examined 

 its nature, But in his ' Epistle to the Reverend Doctor Hales, 

 being Introductory to the Essays on the Blood,' Davies says that 

 he had drawn the principal lines of the first essay full twenty- 

 five years before, and that he hopes the publication of it may 

 engage younger eyes and younger minds in such studies, adding, 

 in a postcript, dated March 1, 1759, that the first essay was 

 then in the press. I know not that he ever published another. 

 Twenty-five years before the date of the epistle to Hales would 

 be in 1734, when Dr. Hunter was but sixteen years of age. 

 1 Elementa Physiologic, torn, ii, pp. 42, 125, 4to, Lausannae, 1760. 



