THE BLOOD. 15 



It is this coagulable lymph which forms the inflammatory 

 crust, or buff, as it is called. It likewise forms polypi of the 

 heart, and sometimes fills up the cavities of aneurisms, and 

 plugs up the extremities of divided arteries. It is supposed, 

 by its becoming solid in the body, to occasion obstructions 

 and inflammations ; and even mortifications, from the exposi- 

 tion to cold, have been attributed to its coagulation. In a 

 word, this lymph is supposed to have so great a share in the 

 cause of several diseases, that it would be a desirable matter to 

 be able to ascertain the causes of that coagulation, either in 

 the body, or out of it. 



The blood, when received into a basin, and suffered to rest 

 in the common heat of the atmosphere, very soon jellies or 

 coagulates ; the part which now becomes solid is the coagulable 

 lymph, as has been shown above. The circumstances in which 

 it now differs from what it was in the veins, are these : it is 

 exposed to the air, to cold, and is at rest ; for whilst in the 

 body, air is excluded, it is there of a considerable warmth, 

 and is always in motion. The question is, to which of these 

 circumstances its coagulation whilst in the basin is chiefly 

 owing? This question, I believe, cannot well be answered 

 from the experiments that have hitherto been made. It has 

 indeed been said, that the cold alone coagulated it; for, say 

 they, if you receive blood into a basin, and set that basin 

 in warm water, and stir the blood well, it can be kept fluid. 

 But in the experiments from which this conclusion was made, 

 I find there has been a deception 1 . In short, I have found that 

 it coagulates as soon when kept warm and when agitated (ix), 



1 That is, the lymph really had been coagulated, but by the agitation had likewise 

 been separated from the rest of the blood, and had thereby escaped notice. 



discs. Fibrin undergoes modifications in its chemical properties after its 

 separation from the blood, being especially less susceptible of the action 

 of acetic acid, as mentioned in the Note to Gerber's Anatomy, p. 95. 



A notice is given in the Introduction, of the incorrect views of Sir 

 E. Home and others ; as well as of the singular claim of M. Denis to 

 the discovery of the liquidity of the fibrin in the 'Circulating blood. 



(ix.) The opinion that agitation prevents coagulation was entertained 

 by Lower/ and stated as a well-known fact 159 years afterwards, by 

 Dr. Bostock. 5 Senac c adduced the supposed fact as a proof of the 



a De Corde, 8vo, Lond. 1669, p. 173. 



b Elementary System of Physiol. i, 438, 440, 2d ed. 8vo, Lond. 1828. 



c Traite du Cceur, ed. 1749, ii, 134. 



