CHAP. II. J THE BLOOD. 57 



posing that blood does possess a strong tendency to coagulate and 

 that the tendency which the blood has to coagulate is inhibited by a 

 peculiar influence exerted by the living vascular walls. Lister on 

 the contrary maintains that blood possesses no spontaneous tendency 

 to coagulate and only does so when brought in contact with any 

 foreign body ; it coagulates within a blood-vessel when the latter dies 

 because then its walls become as all other extraneous matter, but not 

 because there is any cessation of an action previously exerted. 



After all, there appears to be less difference between the views of 

 Lister and Briicke than would at first appear to be the case. Let us 

 examine however which of their views appears most probable in the 

 light afforded by recent discoveries. 



Of all the facts which have, thanks to the labours of Buchanan, 

 Schmidt, and Hammarsten, been collected, in reference to the exact 

 mode of origin and nature of coagulation, none appear to be so 

 consistent and satisfactory as those which connect the colourless cells 

 of the blood with the developement of a ferment-like body which, once 

 liberated, soon converts soluble into insoluble proteid matter; the 

 developement of ferment being apparently connected with a disinte- 

 gration of certain of the colourless cells. 



As this disintegration has a tendency to occur whenever the blood 

 removed from the living blood-vessels is kept at temperature above 

 C., we can scarcely agree in the proposition of Professor Lister 

 that the blood has of itself no tendency to coagulate, and we should 

 rather be inclined to say that inasmuch as it contains colourless 

 corpuscles within it, it does contain the elements for its future 

 coagulation. 



The remarkable phenomena of the non-coagulation of blood with- 

 in the yet living venous walls is probably connected with a persistence 

 in an intact condition of the colourless cells, or rather of those cells 

 in which the fibrin-ferment originates, and not as might have been 

 supposed, upon the destruction of the fibrin-ferment by the vascular 

 walls at the moment of its liberation. But it is yet impossible to 

 conceive why the colourless corpuscles should not break down under 

 the circumstances of Lister's experiments. 



SEC. 3. THE SERUM AND THE CONSTITUENTS OF THE LIQUOR 

 SANGUINIS WHICH REMAIN IN IT. 



Modes of The serum is the liquor sanguinis from which fibrin 



obtaining se- has separated; it differs from that fluid in having 

 nun - lost its fibrinogen and perhaps in having gained some 



paraglobulin. 



In order to obtain perfectly pure serum when horse's blood is 

 available, liquor sanguinis may be first separated by subjecting the 

 blood to a lower temperature in the apparatus described at page 32, 

 and the plasma allowed to coagulate. 



