192 OF THE BLOOD. 



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 sanguinis, and especially in that of the fibrin (on which the viscidity 

 of the blood appears chiefly to depend), might be expected to produce obstruc- 

 tion in the capillary circulation, and to favor transudation of the fluid portion 

 of the blood; and the numerous experiments of Magendie 1 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 

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

 sanguinis ( 139) ; and the perfect elaboration of the albuminous constituent 

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

 uding the membranous walls of the vessels which it traverses ( 167). These 

 and other physical and chemical relations of the Blood, however, are quite sub- 

 ordinate to its Vital reactions; and it is into them that we have now to inquire. 

 180. There are only two constituents of the circulating Blood, which can be 

 considered as being themselves endowed with vital properties ; these are, the 

 Fibrin and the Corpuscles. The remainder of its components can scarcely be 

 looked upon in any other light than as chemical compounds, which are to be 

 rendered subservient to the nutritive and other operations of the living tissues 

 in virtue of their vitality, or which have already discharged their duty in the 

 system. To attribute vital properties to a substance which, like Fibrin, is 

 usually in a state of solution, has been .considered by some Physiologists as an 

 absurdity ; but there seems no adequate reason why liquids, as well as solids, 

 should not possess vital attributes ; a and it has been already shown, that the 

 power exhibited by fibrin, of spontaneously passing (under certain conditions) 

 into an organized texture, however low its type, cannot be legitimately considered 

 in any other light than as a vital endowment ( 2629). That the Corpuscles, 

 however, both Red and Colorless, are living cells, and that, like other cells, 

 they possess vital endowments peculiar to themselves, is not now questioned by 

 any one; and their separate history forms no unimportant element in the gene- 

 ral " Life of the Blood," whilst it can scarcely be doubted, from the facts 

 already stated, that it has a most important relation to the Life of the body 

 generally. Before proceeding, however, to inquire into the nature of this rela- 

 tion, 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." This term, however, as applied 

 to the blood en masse, is quite inappropriate; since, as we shall presently see, 

 the coagulation essentially consists in the passage of the fibrin alone from the 

 soluble to the solidified state ; and this component scarcely forms more than one 

 hundredth part of the whole solid matter of the circulating fluid. All the 

 phenomena attendant upon this process, and the conditions by which it is influ- 

 enced, have been made the subject of very careful study, both by Chemists 

 and Physiologists ; but it must be admitted that they throw very little light 



1 "Le9ons sur les Phenomenes Physiques de la Vie." 



2 If, as the recent observations of Mr. Newport ("Phil. Trans." 1851, p. 241) appear 

 to show, the spermatozoa in contact with the ovum undergo "diffluerice" preparatory to 

 the exertion of their fertilizing power, we have a most remarkable example of the pos- 

 session, by a liquid, of endowments which must be considered as more purely vital than 

 those of the spermatozoa themselves ; for the latter, so long- as they retain their organic 

 form, manifest their vitality in no other way than by the performance of rhythmical move- 

 ments. It would seem, in fact, as if the fertilizing material, prepared by the agency of 

 the seminal cells, had been temporarily cast into the solid form, for the sake of enabling 

 it to find its way, by spontaneous movement, to the ovum it is destined to impregnate. 



