INTRODUCTION. 



XXV 



subjects, in a letter to Dr. Hay garth, which appeared in the third 

 volume of the same work. 



Concerning the coagulation of the blood, so admirably illus- 

 trated by Hewson's labours, it is remarkable that the historical 

 part has been strangely neglected. From this remark the in- 

 teresting notices by Dr. Davy 1 must be excepted ; but they are 

 only sufficient to show, what it is probable he intended, that 

 further inquiry on the subject is wanted. In short, so im- 

 perfect are the records of this branch of science, that physio- 

 logical literature, overflowing about the red particles, is yet 

 destitute of a connected history of the spontaneously coagulable 

 principle of the blood. This, up to the year 1832, I shall now 

 attempt to supply. It will be a curious chapter in physiological 

 history, showing the uncertainty of fame and the slowness of 

 justice -, the delusion of hypothesis and the advantage of ob- 

 servation and induction. Such a narration is moreover abso- 

 lutely necessary to enable us to form a correct estimate of the 

 merits of Hewson, and of some of his contemporaries, as original 

 inquirers. He entertained a just view of tjie nature of false 

 membranes on serous surfaces; 2 but as he has given no opinion 

 concerning the organization of the blood- clot or of the fibrin, it 

 is unnecessary on the present occasion to consider the important 

 researches of Mr. Hunter on this point, the more especially as 

 they are familiarly known in the physiological schools of Britain. 



Aristotle 3 seems to have ascribed the coagulation of the 

 blood to the presence of a fibrous matter. It is not certain 

 whether he considered this matter as existing in the circulation, 

 or as liquid there, andformed in the blood after it is extravasated. 

 He noticed that it will not coagulate if the fibres be removed. 



Harvey 4 supposed that the living blood contains none of the 

 parts found in it after death. These he described as a cruor 

 of red and white portions, one dense and fibrous, the other 

 ichorous and serous, the fibres connecting the whole. It may 

 be inferred that he was acquainted with the effect of heat upon 

 serum, and indeed it is not improbable that Aristotle was. 



1 Researches, Physiol. and Anat. vol. ii, p. 49, 8vo, London, 1839. 



3 See Note LXXII, page 162. 



3 Oper. om. I, p. 457, fol. Aureliae Allobrogum, 1605. 



H De Generatione Animalium, pp. 159-60, 4to, Lond. 1651. 



C 



