274 OF THE BLOOD: ITS VITAL PROPERTIES, 



the fluidity of the blood, only continues during such time as their solutions re- 

 tain a certain strength ; for if they be diluted coagulation will then take place, 

 although in most cases less perfectly than it would have done at first. There 

 appears to be no limit to the time during which the coagulation may be thus 

 postponed; thus Mr. Gulliver 1 mentions that he has kept horse's blood fluid 

 with nitre for fifty-seven weeks, and that it still readily coagulated when di- 

 luted with water. 2 It is not so difficult, therefore, as it might otherwise seem, 

 to give credit to the statement of Dr. Polli, that, in a case witnessed by 

 himself, complete coagulation of the blood did not take place until fifteen 

 days after it had been withdrawn from the body; and that fifteen days 

 more elapsed before putrefaction commenced in it. The upper four-fifths 

 of the clot were colorless, the red corpuscles occupying only the lowest fifth. 

 It is additionally remarkable that the patient (who was suffering nnder 

 acute pneumonia) being bled very frequently during the succeeding week, 

 the blood gradually lost its indisposition to coagulate. 3 Neither heat, am- 

 monia, nor carbonic acid appear to be evolved, as was formerly supposed, 

 during coagulation. 



209. The vital condition of the walls of the bloodvessels appears to have 

 an important influence upon the fluidity of the Blood. Thus it has been 

 found by Sir A. Cooper and Mr. Thackrah, and the same point has been 

 strongly insisted upon by Bru'cke, 4 that whilst blood inclosed in a living 

 vein may retain its fluidity for some time ( 208), blood similarly inclosed in 

 a dead vein, the atmosphere being completely excluded, will coagulate in a 

 quarter of an hour. Moreover, inflammation of the walls of the bloodves- 

 sels (which is a condition of depressed vitality, chap, x) promotes the coag- 

 ulation of the blood which they contain, and thus it is, that the trunks both 

 of arteries and veins frequently become choked up by coagula. And, although 

 there can be no doubt that a large proportion of the loose fibriuous masses 

 found in the heart and large vessels after death, are the result of post-mor- 

 tem coagulation, yet there is often adequate evidence, derived from the symp- 

 toms previously observed, and from the appearances presented by the coagula 

 themselves, that the coagulation has commenced during life ; and in all cases 

 of this kind there has been a marked depression of vital pow 7 er for some time 

 previous to the final extinction of life. Again, it was found by Schroeder 

 Van der Kolk, 5 that if the substance of the brain and spinal marrow be 

 broken down, coagulation of the blood takes place whilst it is still moving 

 within the vessels; clots being found in them, even within a few minutes 

 after the operation. Further, that the contact of a dead substance promotes 

 coagulation, 6 even in the living and actively moving blood, is shown by the 

 experiments of Mr. Simon, who carried a single thread (by means of a very 



1 Mr. Gulliver considers this fact, together with the occurrence of coagulation on 

 the thawing of blood which has been frozen whilst yet fluid, as conclusive against 

 the vital character of the act; remarking that if we believe the coagulation to be an 

 efleet of life, we must admit that we can freeze and pickle the life (op. cit., p. 21). 

 No such admission, however, is necessary. We do not freeze and pickle the life; 

 but we simply preserve the vital properties of the substance by preventing it from 

 undergoing spontaneous change; thus doing the same for the blood as may be done 

 for seed.-;, eggs, and even highly-organized bodies, which may be kept in a state of 

 " dormant vitality " for unlimited periods, by cooling or drying them, or by secluding 

 them from the atmosphere. (See Princ. of Gen. Physiol.) 



- Op. cit., p. 12. 



<!a/.ett:i Medica di Milano, Genn. 20, 1844; cited in Mr. Paget's Report in Brit, 

 and For. Med. Rev., vol. xix, p. 252. 



4 Vorlosungen, 1874, p. 81 et seq. 



5 Comment, de Sunguinis Coagulatione, Groningen, 1820. 



6 For various proofs of which see Lister, Croonian Lecture on the Coagulation of 

 the 131ood, in Lancet for 1863, vol. ii, p. 179. 



