ALTERATIONS OF ITS COMPOSITION IN DISEASE. 265 



cided variations take place in the quantity or quality of its principal com- 

 ponents, and of the effects which those variations produce upon the system 

 at large. Many analyses have been made by excellent observers ;' but in 

 consequence of the variations in the mode of analysis pursued, the results 

 can only be given in general terms. 



199. The first of these components whose variations we shall consider, is 

 Fibrin : the estimate of which, however, is open to an important fallacy, 

 that has not been sufficiently guarded against, namely, the admixture of the 

 Colorless corpuscles. "These," as Mr. Paget correctly remarks, "cannot, 

 by any mode of analysis yet invented, be separated from the fibrin of mam- 

 malian blood ; their composition is unknown, but their weight is always in- 

 cluded in the estimate of the fibrin. In health they may, perhaps, add too 

 little to its weight to merit consideration ; but in many diseases, especially 

 in inflammatory and other blood diseases in which the fibrin is said to be in- 

 creased, these corpuscles become so numerous that a large proportion of the 

 supposed increase of the fibrin must be due to their being weighed with it. 

 On this account, all the statements respecting the increase of fibrin in cer- 

 tain diseases need revision. 2 In the results of the analyses now to be stated, 

 it must be borne in mind that the term "fibrin" really designates the "col- 

 orless coagulum" of spontaneous formation, whatever may be its composi- 

 tion. The following may be considered as the normal range of variation for 

 the principal constituents of the blood in health, according to the mode of 

 estimating them pursued by MM. Audral and Gavarret: 



Fibrin, . . from 2 to 3J- parts per 1000. 



Red corpuscles, . " 110 ' 152 " " 



Solids of serum, . " 72 " 88 " " 



Water, . . " 760 " 815 " " 



200. The most important fact substantiated by Andral, is one that had been 

 previously suspected, the invariable increase in the quantity of Fibrin 

 during acute Inflammatory affections, as pleurisy and pneumonia, the in- 

 crease being strictly proportional to the intensity of the inflammation, and 

 to the degree of symptomatic fever accompanying it. "The augmentation 

 of the quantity of Fibrin is so certain a sign of Inflammation, that, if we 

 find more than 5 parts of fibrin in 1000 in the course of any disease, we 

 may positively affirm that some local inflammation exists." The average 

 proportion of Fibrin in inflammation may be estimated at 7; the minimum 

 at 5; the maximum at 13.3. The greatest augmentation is seen in Pneu- 

 monia and Acute Rheumatism. Such blood in general coagulates slowly. 3 

 An increase is also commonly observable during the advanced state of 

 Phthisis, in spite of the deterioration which the blood must then have un- 

 dergone, and this is probably dependent upon the development of local 

 inflammation around the tubercular deposits. In continued and Typhoid 

 Fevers, whilst the proportion of Corpuscles is commonly increased, there is 

 a decrease in the proportion of Fibrin, especially in the early stage; though 

 the usual augmentation will take place if any local inflammation occurs. 

 It appears from the experiments of Magendie, that one of the effects of a 



1 See Andral and Gavarret, Essai d'Ha?matologie Pathologique ; Becquerel and 

 Rodier, Recherches sur la Composition du Sang, etc. 



2 Kirkes and Paget's Handbook of Physiology, p. 57. 



3 The white fibrinous clots found after death in the heart and large arteries, in 

 various diseases, appear to owe their origin to the slight disposition of the blood in 

 these cases to coagulate, thus affording time for the sinking or separation of the 

 red corpuscles. Mayer lias augmented the amount of fibrin in the blood of dogs to 

 nearly double its normal amount by repeated bleedings, repeated at stated intervals 

 (quoted in Brucke's Yorlesungen, 1874, p. 117). 



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