AND ITS RELATIONS TO THE LIVING ORGANISM. 271 



Albuminous, Saline, and Extractive matters, still dissolved in the water, are 

 more or less completely expelled from it, constituting the Serum. This sepa- 

 ration will not occur, however, if the coagulation take place in a shallow 

 vessel; nor if the amount of Fibrin should be small, or its vitality low. A 

 homogeneous mass, deficient in firmness, presents itself under such circum- 

 stances ; though the solid part of this may pass into a state of more com- 

 plete condensation after a lapse of a certain time. That the coagulation is 

 due to the Fibrin, and that the Corpuscles do not take any active share 

 in the process, appears from several considerations. 1 A microscopical exami- 

 nation of the clot shows, that it has the same texture with Fibrin when 

 coagulating by itself; the Corpuscles clustering together in the interspaces 

 of the network, and not being uniformly diffused through the whole mass. 

 Their specific gravity being greater than that of the Fibrin, they are usually 

 most abundant at the lower part of the clot, and the' upper surface is some- 

 times nearly colorless, especially when the coagulation has taken place 

 slowly; yet this upper part is much firmer than the lower, showing that the 

 fibrin alone is the consolidating agent. If, after the complete subsidence of 

 the Corpuscles, a little of the colorless Liquor Sanguinis be skimmed off, it 

 will undergo complete coagulation, forming a colorless clot, as was long ago 

 shown by Hewsou. The same fact may be experimentally demonstrated, 

 by the use of methods which effect an artificial separation of the Fibrin 

 from the Corpuscles. Thus Mu'ller placed the blood of a Frog, diluted with 

 water (or still better, with a very thin syrup), on a paper filter, when the 

 Liquor Sanguinis, having passed through completely unmixed with the cor- 

 puscles, presented a distinct coagulum; although, from the diluted state of 

 the fluid, this did not possess much consistency. Owing to the more minute 

 size of the Blood-disks of warm-blooded animals, this experiment cannot be 

 so readily performed with their blood. So, again, if fresh-drawn blood be 

 continually stirred with a stick, the Fibrin will adhere to it in strings dur- 

 ing its coagulation ; and the Red corpuscles will be left suspended in the 

 serum, without the slightest tendency to coagulate. Moreover, if a solution 

 of any salt that has the property of retarding the coagulation (such as car- 

 bonate of potash or sulphate of soda) be added to the blood, the Corpuscles 

 will have time to sink to the lower stratum of the fluid before the clot is 

 formed; the greater part of the crassamentum is then entirely colorless, and 

 is found by the microscope to contain few or no red particles. A curious 

 observation has been made by Bernard, showing that, even during life, the 

 Blood-cells gravitate to the lowest part of the fluid. Thus in a Horse, laid 

 out on the ground in such a position that its long jugular vein was nearly 

 horizontal, a small opening made in the upper surface allowed the escape 

 only of yellowish serous fluid without red corpuscles, whilst from a similar 

 small opening made at the lowest surface of the vein some very black blood 

 issued. Both portions coagulated; the first, of course, giving a colorless 

 clot; the second, as usual, a dark clot, with a well-marked bufly coat. 2 It 

 will be presently shown, however, that the difference of specific gravity is 

 by no means the only cause of the separation of the Corpuscles from the 

 Liquor Sauguinis. Generally speaking, the fibrillation is more perfect the 

 more slowly it takes place; and the higher the previous vitalization of the 



1 It is remarkable that this doctrine, clearly established by the older Physiologists, 

 and especially by Hewson, should ever have been put aside, even temporarilj", for 

 the untenable hypothesis that the coagulation of the blood is due to a running together 

 of its red corpuscles. For an admirable summary of the history of opinion on this 

 subject, see M. Gulliver's Introduction to his Edition of Hewson's works (published 

 by the Sydenham Society). 



2 Bernard, Lemons, 1859, p. 432. 



