5() NON-COAGULATION OF BLOOD IN LIVING VESSELS. [BOOK I. 



proof. On returning, however, to other ohservations of Lister we are 

 warned to pause before we draw the above conclusion. The author 

 quotes Professor Lister's description of one of his experiments conveyed 

 to him in a private communication: 



" The manner in which I did succeed in my experiments long ago on 

 the coagulation of the blood in maintaining its fluidity outside the living 

 body seems to me, if I may venture to say so, deserving of more attention 

 than I think it has received. Having ascertained that the blood remains 

 fluid for many hours after somatic death in all vessels except the heart 

 and principal trunks provided that the vessels have been previously 

 healthy, I removed a portion of the jugular vein of an ox, after tying it 

 in two places to retain the blood ; and then, holding the portion of vein 

 vertical and opening the upper end with scrupulous care that the instru- 

 ments employed should not touch the blood, I slipped down with the 

 utmost steadiness a piece of glass tube nearly as large in calibre as the 

 vein, the lower end of the tube being of full width and smooth while the 

 upper end was drawn out and connected by an india-rubber tube with a 

 stop-cock for closing it. The blood having filled the large part of the tube 

 and passed on into the narrow part till it escaped at the stop-cock, the 

 stop-cock was turned to close ifc, after which the whole apparatus was 

 rapidly inverted so that the blood was now in the glass vessel with 

 its mouth covered with the vein as a cap. The vein was next care- 

 fully withdrawn and a cap of gutta-percha tissue was tied over the 

 mouth of the tube to prevent evaporation. The blood was now in a 

 vessel composed entirely of ordinary solid matter, as distinguished from 

 living tissue, but with the peculiarity as compared with blood shed into 

 a basin that only the circumferential parts of the mass of blood had been 

 exposed to the influence of the ordinary solid. The result was that 

 after 24 hours, or in one experiment 48 hours, the blood was found still 

 fluid except a crust of clot in contact with the containing vessel, the fluid 

 blood coagulating at once on being poured upon a plate. I had previously 

 ascertained that blood would remain fluid for hours in a vein after being 

 exposed with the utmost freedom to the air by being poured in thin 

 streams from one venous capsule (if I may so speak) to another ; while, 

 on the contrary, want of steadiness in pushing down the glass tube into 

 the vein and consequent admixture of the circumferential parts which 

 had touched the glass with the rest would, like a stir with a stirring rod, 

 have made the whole coagulate. 



"Thus by this simple experiment was demonstrated incontrovertibly 

 the fact that healthy blood has no spontaneous tendency to coagulate and 

 therefore that Briicke's idea of the fluidity of the blood being due to an 

 action of the walls of the vessels upon it was erroneous. At the same 

 time was illustrated the truth, which, indeed, ought to have been apparent 

 enough from the results of every vivisection wound, that a perfectly 

 undisturbing coagulum resembles healthy living tissue in failing to induce 

 coagulation in its vicinity." 



The difference between Lister's and Briicke's explanation of the 

 above facts will be perhaps more apparent by the following categori- 

 cal statement. Briicke explains the non- coagulation of the blood 

 contained in the uninjured and yet living jugular vein by sup- 



