ITS VITAL PROPERTIES, AND RELATIONS TO LIVING ORGANISM. 197 



doubt that a large proportion of the loose fibrin ous masses found in the heart and 

 large vessels after death are the result of post-mortem coagulation, yet there is 

 adequate evidence, derived from the symptoms observed during life, 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 power for some time previous to the final extinction of life. 

 Again, it was found by Schrreder Van der Kolk, 1 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, 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 fine needle) transversely through an adjacent artery and vein 

 of a dog, and left it there, so that it might cut the stream, for a period of from 

 twelve to twenty-four hours; the consequence of which was that a coagulum 

 was formed upon the thread, more or less completely obstructing the vessel. 

 There was, however, a marked difference in the coagula formed within the artery 

 and the vein respectively, which may be attributed to the difference in the 

 quality of the fibrin in the blood of the two vessels ( 164), or to the differ- 

 ence in the rate of its motion, or to both causes conjointly ; for the thread which 

 traversed the artery usually presented a " vegetation" on its surface, sometimes 

 as large as a grain of wheat, always of a pyramidal shape, with its base attached 

 to the thread, and its apex down-stream ; whilst the venous coagulum was a 

 voluminous black clot, chiefly collected on that side of the thread remotest from 

 the heart. 2 



187. Again, the contact of dead animal matter with the blood appears to 

 promote the coagulation of its fibrin in a very remarkable degree j occasioning 

 coagula to form whilst it is yet actively moving in the vessels of the living body. 

 Thus M. Dupuy found that the injection of cerebral substance into the veins of 

 an animal occasioned its death almost as instantaneously as if prussic acid had 

 been administered ; the circulation being rapidly brought to a stand by the forma- 

 tion of voluminous clots in the heart and large vessels. These experiments 

 were repeated and confirmed by M. de Blainville. 3 The same effect is produced 



at the Middlesex Hospital in 1835, witnessed a remarkable case of Phlebitis (apparently 

 brought on by suppressed menstruation), in which both femoral veins were successively 

 affected, and in which death took place suddenly when the patient appeared to be recover- 

 ing from the attack ; on post-mortem examination, not only the iliac trunks, but also the 

 vena cava, for some distance above their junction, were found to be completely obstructed 

 by nearly colorless coagula adherent to their walls ; so that the wonder was, how any re- 

 turn of blood could have taken place from the pelvis and lower extremities. There seemed 

 no reason to attribute the formation of these coagula to the introduction of pus into the 

 venous circulation. 



1 "Comment, de Sanguinis Coagulatione," Groeningen, 1820. 



2 "Lectures on General Pathology," p. 48, Am. Ed. Mr. Simon applies this fact to 

 the explanation of the "vegetations" which so commonly present themselves upon the 

 valves of the heart, in cases of rheumatic endocarditis ; maintaining that they are simple 

 deposits from the fibrin of the blood, which is unusually abundant in this condition. This 

 doctrine can only be substantiated, however, by a careful microscopic examination of these 

 substances ; and if they should be proved to have the simple constitution which Mr. Simon 

 imputes to them, the fact will in no degree set aside (as he seems to consider it must do) 

 the existence of endocardial inflammation, but will rather confirm it, since the deposition 

 of fibrin on those particular spots is likely to be specially determined by inflammation of 

 the subjacent membrane. 



3 "Gazette Medicale," 1834, p. 521. There is no reason to suppose that cerebral sub- 

 stance possesses a more special influence than would be exerted by any other tissue which 

 could be as easily mixed up with the circulating current. It will be remembered that the 

 presence of a piece of flesh, or of the clot of blood, determines the coagulation of fibrin 

 in a solution from which it would not otherwise have separated ($ 26). 



