FIBRIN. 361 



attain at least the same height as in pneumonia, we know that fever, 

 notwithstanding it is often accompanied by an increased frequency 

 in the respirations, by no means gives rise to an augmentation of 

 the fibrin. Physiological facts lead us to exactly the opposite hypo- 

 thesis that the augmentation of the fibrin in inflammatory blood is 

 to be referred to a diminution in the supply of oxygen. The frequent 

 but short and incomplete respirations which occur only in febrile 

 (and not in non-febrile) inflammations, are only sufficient to convey 

 to the blood sufficient oxygen to convert certain substances into 

 fibrin but not to oxidise them further; this is the reason why the 

 amount of fibrin attains its maximum in pneumonia and pieuritis, 

 and why the blood in the former disease is most rich in carbonic 

 acid, for this gas is scantily excreted in proportion as oxygen is 

 scantily received by the lungs. The physiological importance of 

 fibrin affords arguments altogether in favour of this view. 



Uses. The phrases, progressive and regressive metamorphosis, 

 of whose import we have spoken in an early part of this volume, 

 (see p. 27 J have led to a long contest regarding the physiological 

 importance of fibrin. On the one hand, it has been correctly 

 maintained that this substance must be necessary to the formation 

 of tissues, since as a general rule, the only exudations which are 

 capable of organisation are those which contain fibrin ; on the other 

 hand, stress is laid upon the circumstance that an augmentation of 

 the fibrin coincides with those states in which nutrition and reno- 

 vation are most affected, and on the incontestable fact that the 

 fibrin in the blood is found to be increased when more albuminous 

 matters have been taken as food than could be applied to the repa- 

 ration of effete tissue. We regard it, however, as superfluous to 

 enter into the detailed arguments for and against these two opinions. 

 The bearing of the whole case is simply this. It is pretty well 

 established that fibrin is formed by a process of oxidation from albu- 

 minous matters ; now we know that almost all the tissues are richer 

 in oxygen than fibrin, and on the other hand, that the effete mate- 

 rials of tissue and the excess of nutrient matter can only be removed 

 from the system, that is to say, be converted into ordinary excreta, 

 by oxidation. Hence, the simplest view is to regard fibrin as 

 representing a transition stage. If an albuminous body in the 

 animal organism be more highly oxidised, it cannot altogether 

 exceed the transition stage which is represented by fibrin, although 

 indeed, the formation and increase of the latter may not always be 

 evident. An analogous instance from pure chemistry will elucidate 

 this view ; we know, from Licbig's celebrated investigations on fer- 



