ITS VITAL PROPERTIES, AND RELATIONS TO LIVING ORGANISM. 201 



and then only influencing the relative situations of the two components of the 

 clot. The deficiency in coagulating power, by which the blood is sometimes 

 marked, must be attributed to the want of due elaboration in the Fibrin alone, 

 or to the destruction of its vital endowments by some agent which has a nox- 

 ious influence upon it ; of the former condition we seem to have an example in 

 such a case as that already cited ( 176), in which the circulating fluid consisted 

 of a very crude chyle ; of the latter, in those diseased states in which we can 

 trace the operation of a poison upon blood that was previously healthy, as when 

 asphyxia has occasioned the retention of carbonic acid generated within the 

 system, or when the materies morbi of cholera or some malignant fever has been 

 introduced into the circulation. But it would be by no means fair to attribute 

 the noxious influence of such poisons solely to their power of destroying the 

 coagulability of the blood-fibrin, for it is obviously exerted in many other ways; 

 and it is probable that the same agency which kills the fibrin exerts a similar 

 destructive power on the vitality of the corpuscles, and on that of the tissues 

 through which the poisoned blood circulates. But whilst we attribute the co- 

 agulating power of the Blood to the vital endowments of the fibrin, we can 

 scarcely fail to perceive that the exercise of this power is kept in check (so to 

 speak) by the vital endowments of the living tissues with which it is in contact. 

 For, as we have seen, the main condition of coagulation is the diminution or 

 cessation of their agency, either by the withdrawal of blood from the body, or 

 by the death of the organism enclosing it, or by the lowered vitality of the tis- 

 sues through which it moves ( 186) ; whilst mere stagnation exerts but a 

 secondary influence upon it ( 184). And thus we seem entitled to say, that 

 the liquid condition of the fibrin is a result of a balance of forces between the 

 fibrin and the living tissues, those of the former tending to its solidification, 

 whilst those of the latter maintain its fluidity ; but that if the latter should be 

 deficient, the former come into uncontrolled action, and expend themselves in 

 the production of a lowly-organized tissue, the higher vitalization of which de- 

 pends upon subsequent operations ( 29). The source of this vital endowment 

 of the Fibrinous constituent of the blood must be looked for in the operations 

 to which the crude albuminous pabulum is subjected, after its first reception into 

 the system ' } and these will hereafter become the subject of inquiry. 



192. Of the particular purposes which are served by the Fibrin of the blood 

 in the vital economy of the system at large, it must be confessed that we have 

 but little positive knowledge. The idea has been entertained by many Physi- 

 ologists (including the Author of this treatise) that the fibrin is that element 

 of the blood which is immediately drawn upon in the operations of nutrition ; 

 being the intermediate stage between the crude albumen and the solid tissues. 

 This opinion rested in part upon the current doctrine, that fibrin is the consti- 

 tuent of Muscle; and in part upon the assumption, that, as fibrin is more en- 

 dowed with vital properties than any other of the liquid components of the 

 blood, so as to be capable of passing by itself into the condition of an organized 

 tissue, it must be the one most readily appropriated by the various parts of the 

 solid fabric, as the material for their growth and development. Various con- 

 siderations have of late been adduced, however, which tend to shake this belief. 

 It has been shown that so far from there being any evidence of the identity of 

 the fibrin of blood and the substance of muscle, the evidence is precisely the 

 other way ( 25). Again, we have seen that there are both structural and 

 chemical indications, that fibrin is in a state of transition rather towards the 

 fibro-gelatinous textures, than towards those of the cellulo-albuminous type; 

 for the fibrous network which is formed by its coagulation bears a greater resem- 

 blance to the white fibrous tissue ( 220), than to any other texture of the body; 

 whilst the points in which the chemical properties of fibrin differ from those of 

 albumen are such as manifest a relationship to gelatin ( 25 30). We seem 



