THE BLOOD. 17 



cannot be supposed to be the cause of the coagulation out of 

 the body. 



To see the effects of cold on the blood, I made this experi- 

 ment : 



EXPERIMENT V. 



I killed a rabbit, and immediately cut out one of its jugular 

 veins, proper ligatures being previously made upon it ; I then 

 threw the vein into a solution of sal ammoniac and snow, in 

 which the mercury stood at the 14th degree of Fahrenheit^ 

 thermometer. As soon as the blood was frozen and converted 

 into ice, I took the vein out again, and put it into lukewarm 

 water till it thawed and became soft ; I then opened the vein, 

 received the blood into a teacup, and observed that it was 

 perfectly fluid, and in a few minutes it jellied or coagulated as 

 blood usually does. Now, as in this experiment the blood 

 was frozen and thawed again without being coagulated, it is 

 evident that the coagulation of the blood out of the body is 

 not solely owing to cold (xi) any more than it is to rest. 



In the heart of a man fifteen hours after death, when the limbs were 

 stiffened, I have seen fluid blood which coagulated after exposure. 

 Dr. Davy c has made several exact observations to the same effect, one 

 twenty-nine and several twenty-six hours after death. Dr. B. G. 

 Babington d has recorded an instance of the same kind in bloody 

 fluid from the brain. Occasionally blood is extravasated and stag- 

 nated in the living body for an indefinite time, and yet retains 

 its fluidity, as Mr. Hunter 6 and Mr. Caesar Hawkins have noticed. 

 I saw a case in a soldier who had received a bruise in his loins, from 

 his horse bolting with him over a bridge in Hyde Park ; the injured 

 part quickly swelled, evidently from effused fluid, which was let out 

 twenty-eight days afterwards. It measured five ounces ; was as liquid 

 as blood just drawn from a vein, and coagulated in a cup in less than 

 thirty minutes. The corpuscles were observed to be unchanged, and 

 readily collecting together in the usual way by their broad surfaces ; 

 next day, the clot was moderately firm, scarlet at the top, somewhat 

 contracted, and surrounded by a little serum. 



The effect of agitation on coagulation is mentioned in Note ix. 



(xi.) Aristotle, a Harvey, b and Sydenham, c/ attributed the coagulation 

 of the blood to the escape of its native animal heat or to the cold of the 



c Researches, ii, 206, 122. b De Gener. Animal, p. 404, Op. ora. a 



d Cyclopaedia of Anatomy, i, 421. Coll. Med. Lond. edit. 4to, 1766. 



e Works, ed. by Palmer, iii, 33. c ' Op. omnia, imp. Soc. Sydenhamianae, 



a De Part. Animal, lib. ii, c. 4. 8vo, Lond. 1844, p. 247. 



2 



