PROPERTIES OF THE BLOOD. 445 



red particles is due to this cause alone. Dr. Alison,* however, maintains 

 that there must be an absolute tendency to separation between the two compo- 

 nents of the clot, in order to account for the phenomena sometimes presented 

 by it; and he adduces the two following reasons in support of this view. 

 " 1, The formation of the Buffy coat, though no doubt favoured or rendered 

 more complete by slow coagulation, is often observed in cases where the 

 coagulation is more rapid than usual; and the colouring matter is usually 

 observed to retire from the surface of the fluid in such cases, before any coagu- 

 lation has commenced. 2. The separation of the Fibrin from the colouring 

 matter in such cases takes place in films of blood so thin as not to admit of a 

 stratum of the one being laid above the other ; they separate from each other 

 laterally, and the films acquire a speckled or mottled appearance, equally 

 characteristic of the state of the blood with the buffy coat itself." It appears 

 from the observations of Mr. Wharton Jones, that the red corpuscles of Inflam- 

 matory Blood have an unusual attraction for each other, which occasions their 

 coalescence in piles and masses ; so that by this character, the state of the 

 Blood may be detected, from the examination of no more than a single drop of 

 the fluid. Now if we consider, in connection with this increase in the mutual 

 attraction of the Blood discs, the increase in the mutual attraction of the par- 

 ticles of Fibrin (which causes the coagulation of Inflammatory blood to be so 

 much firmer and more decidedly fibrous than that of the healthy fluid), we 

 have a cause sufficient to explain the phenomena noticed by Dr. Alison ; 

 without the necessity of resorting to the idea of an absolute repulsion being 

 present between the two constituents. It is in the Buffy Coat of Inflammatory 

 Blood, that we see the clearest indications of organization ever presented by 

 the circulating fluid. The fibrous network is frequently extremely distinct; 

 and it commonly includes a large number of white corpuscles in its meshes. 

 589. When the Buff arises from other causes, however, its appearance is 

 less characteristic. It appears from the researches of Andral, that the essen- 

 tial condition of its production is an increase in the quantity of Fibrin in 

 proportion to the Red Corpuscles; and not a simple increase of Fibrin. 

 When the Blood contains an excessive quantity of Fibrin, it coagulates slowly; 

 thus the blood of a patient labouring under Rheumatism coagulates more 

 slowly than that of one affected with Typhoid fever. The increase may 

 occur in two ways ; either by an absolute increase in the Fibrin, the amount of 

 the corpuscles remaining unchanged, or not being augmented in the same 

 proportion; or \>y a diminution of the Corpuscles, the quantity of Fibrin 

 remaining the same, or not diminishing in the same proportion. Hence in 

 severe Chlorosis, in which the latter condition is strongly developed, the buffy 

 coat may be as well marked as in the severest Inflammation. Unless the 

 composition of the blood be altered in one of these two ways, it is stated by 

 Andral that the buffy coat is never formed ; the influence of circumstances 

 which favour it not being sufficient to produce it when acting alone. The 

 absence of these circumstances may prevent it, however, when it would 

 otherwise have been formed ; thus, when the Blood flows slowly, the buff is 

 not properly produced ; because the slow discharge gives one portion time to 

 coagulate before another ; and only the blood last drawn furnishes the Fibrin 

 at the upper part of the vessel. Again, in a deep narrow vessel, the buff will 

 form much more decidedly than in a broad shallow one ; because the thickness 

 of the Fibrinous crust will be greater. If the blood be agitated during its co- 

 agulation, the Corpuscles are mixed up with the Fibrin, and the crust is 

 imperfect and soft. The process of the formation of the Buffy coat may be 

 best studied by treating ordinary Blood with some of those agents which re- 



* Outlines of Physiology, 3d edition, p. 89. 



38 



