270 OF THE BLOOD: ITS VITAL PROPERTIES, 



of the interruption, is speedily produced. The results of the retention of the 

 materials of the Biliary and Urinary excretions will be hereafter considered 

 (chap, xi); and at present it will be only remarked that such retention is a 

 most fertile source of slight disorders of the system, that it is largely con- 

 cerned in producing many severe diseases, and that, if complete, it will most 

 certainly and rapidly bring about a fatal result. 



3. Of the Vital Properties of the Stood, and its relations to the Living 



Organism. 



205. It cannot be doubted that the perfect and regular performance of the 

 various actions to which the Blood is subservient, is dependent upon the ad- 

 mixture of its principal components in their due proportions, and upon its 

 freedom from deleterious matters whether formed within the system, or in- 

 troduced into the circulating current from without. And it is not difficult 

 to see how any considerable alteration which affects its physical conditions 

 merely, may thereby produce a most serious disturbance in the regularity of 

 the circulation, and in the functions to which it ministers. Thus it has been 

 shown by the experiments of Poisseuille, 1 that a certain degree of viscidity 

 is favorable to the motion of liquids through capillary tubes; a thin solution 

 of sugar or gum being found to traverse them more readily than pure water 

 will do. Hence any serious alteration in the proportion of the organic and 

 saline compounds dissolved in the liquor sanguiuis, and especially in that of 

 the Fibrin (on which the viscidity of the blood appears chiefly to depend), 

 might be expected to produce obstruction in the capillary circulation, and 

 to favor transudation of the fluid portion of the blood; and the numerous 

 experiments of Mageudie (Op. cit.) seem to favor this view, although they 

 are far from manifesting that character for accuracy and discrimination, 

 which would be required to afford an authoritative sanction to it. A much 

 more determinate influence, however, must be exerted upon the Red Cor- 

 puscles, by any cause which seriously affects the specific gravity of the liquor 

 sauguiuis ( 173) ; and the perfect elaboration of the Albuminous constituent 

 of the serum has been shown to be requisite, to prevent it from copiously 

 transuding the membranous walls of the vessels which it traverses ( 196). 

 These and other physical and chemical relations of the Blood are quite 

 subordinate to its vital reactions; and it is into them that we have now to 

 inquire. Before proceeding, however, to inquire into the nature of the 

 relation of the Fibrin and the Corpuscles the two constituents of the blood 

 that are most highly endowed with vital properties to the "Life of the 

 Blood," our attention may be advantageously directed to that remarkable 

 change in the state of the blood when withdrawn from the vessels of the 

 living body, which is commonly known as its "coagulation." 



206. The Coagulation of the Blood consists in the new arrangement of its 

 constituents, which takes place when it is drawn from the vessels and is left 

 to itself, or when the body itself dies ( 172). This new arrangement essen- 

 tially depends upon the passage of the Fibrin (or of the constituents of 

 Fibrin) from the soluble to the insoluble state, in which it forms, not an amor- 

 phous coagulmn, but a network of fibres more or less definitely marked 

 out; in the meshes of which network are included the Red corpuscles, usually 

 grouped together in columnar masses resembling piles of money. Crassa- 

 iiK-iitnm or Clot thus formed, gradually acquires a degree of firmness pro- 

 portioned to the amount of Fibrin which it contains, and to the degree 

 of its elaboration; and it undergoes a progressive contraction, by which the 



1 See M. Magendie's 1,090118 sur les Phe"noniencs Physiques de la Vie, torn, iv, p. 57. 



