USES OF FIBRINE. 91 



blood is obtained in part from the chyle and the lymph ; but it is 

 also probably formed, in all three of these fluids, from their albu- 

 men. Were we content with a mere chemical hypothesis, we might 

 adopt Lehmann's as the most plausible, viz., that "fibrine is pro- 

 duced by the oxidation of albumen in the aeration of the blood, 

 while the conversion of fibrine into the tissues is also the result of 

 an oxidation of fibrine. But fibrine is increased in inflammation, 

 not because of more oxygen in the blood, but because there is less 

 than usual ; there being barely enough to form the fibrine from the 

 albumen, but not enough to secure the metamorphosis of the latter. 

 Hence the highest amount of fibrine is found in piieumonitis, the 

 disease in which the aeration of the blood is most impeded." But 

 oxidation is mere chemical action; and it is entirely abhorrent to our 

 ideas of nutrition, that the tissues are formed from any immediate 

 principle by an exertion of mere chemical force. Each tissue pos- 

 sesses the power of assimilation, by which is meant the power of 

 forming its own substance from materials in the blood, which are 

 never, as there found, precisely identical in composition with itself. 

 So it is probable that fibrine, possessing vitality, develops itself from 

 the analogous compound, albumen, and fat, and a few saline sub- 

 stances. 1 So, also, it is probable that fibrine undergoes its own 

 metamorphosis, in the blood or out of it, as the tissues do ; and 

 when it is formed in excess in the blood, this may be owing to 

 either an excess in its development, or a diminished metamorphosis, 

 or to both combined. 



Uses of Fibrine. 1. The fibrine in the blood gives to it the power 

 of coagulating, and therefore, within certain limits, of spontaneously 

 arresting hemorrhage. In case of ligation of a vessel, also, it is the 

 fibrine which prevents the escape of blood when the ulceratiye pro- 

 cess excited by the ligature cuts off the vessel. 



2. Fibrine present in exudations forms the nidus in which adven- 

 titious growths are developed, or in which k new tissues are formed, 

 as in case of the reparative process. Fibrine appears also to be the 

 forerunner of the original tissues, or the matrix in which they are 

 at first laid down during intra-uterine development ; but, in the last 

 two cases, the fibrine, after fulfilling its temporary office, disappears. 

 It is probable that the fibrine of the blood does not normally con- 



1 For fibrine is probably a compound, and not a simple substance ; as is also the 

 case with caseine. See " Remarks" following. 



