CAUSE OF THE COAGULATION OF THE BLOOD. 39 



really expresses utter want of knowledge on the subject. The theory that motion is the 

 cause of the fluidity of fibrin in the body, is disproved by the fact that violent agitation 

 of the blood out of the body docs not prevent coagulation ; and thus it is with nearly 

 all the theories that have been advanced. 



The idea which we have to present does not explain why the blood coagulates, but 

 it gives a certain notion of the probable conditions under which plusmine exists in the 

 circulating fluid : 



Plasmine, circulating in the blood-vessels, under normal conditions, is a liquid, and 

 its decomposition into metalbumen and fibrin is abnormal. Plasmine is undoubtedly an 

 important nutritive principle, and is constantly undergoing change as it is used in the 

 nutrition of the nitrogenized constituents of the various tissues and organs, the material 

 thus expended being supplied by the nitrogenized constituents of the food. It is, there- 

 fore, like other nitrogenized constituents of the organism, in a condition of constant 

 metamorphosis ; and all that we can say is that, while in this condition, getting material 

 from some parts and giving off matters in others, it does not undergo those decomposing 

 changes which are observed when it is effused, drawn from the body, or the circulation 

 is arrested, which involve coagulation of the blood. 



The above expresses nearly all that we positively know of the cause of the coagula- 

 tion of the blood ; but the question in fact reduces itself to the rather unsatisfactory 

 proposition that the blood coagulates because, when its nitrogenized principles are re- 

 moved from those constant molecular changes which are characteristic of the class of 

 nitrogenized principles as they exist in the living organism, decomposition takes place, 

 which results in the production of a coagulating matter. It is hardly to be expected 

 that physiologists would be satisfied with this, which is indeed little more than a confes- 

 sion of ignorance ; but it must be remembered that we are very little acquainted with 

 the molecular changes taking place constantly in the living body. When we understand 

 these more thoroughly, we may obtain a better knowledge of the causes of coagulation 

 of the blood, cadaveric rigidity of muscles, and other changes which take place when 

 the processes of nutrition cease. 



Within the last few years, A. Schmidt (1861) has proposed a theory of coagulation 

 which involves the coming together of certain principles called fibrin-factors. This the- 

 ory, which had been indicated by Buchanan, in 1845, has been adopted and more or 

 less modified by Kuhne, Virchow, and others. If blood-plasma, rendered neutral with 

 acetic acid, be diluted with ten times its volume of water at 32 Fahr. and then be treated 

 with a current of carbonic-acid gas, a flocculent precipitate is formed, which has been 

 called paraglobuliue, or fibrinoplastic matter. This substance may be dissolved in water 

 containing air or oxygen in solution. After this precipitate has been separated, if the 

 clear liquid be diluted with about twice its volume of ice-cold water and be again treated 

 for a long time with a current of carbonic acid, a viscid scum is produced, which has been 

 called fibrinogen. A small quantity of paraglobuline added to a solution of fibrinogen pro- 

 duces coagulation of a substance like fibrin. More recently, a third principle, a ferment, 

 has been described by Schmidt, which he considers necessary to this formation of fibrin. 



It is very questionable whether the substances called paraglobuline and fibrinogen ex- 

 ist in the blood as peculiar principles. Eobin considers paraglobuline as identical with 

 metalbumen, which is itself one of the products of the decomposition of plasmine. It 

 is true that the so-called paraglobuline added to the liquid of hydrocele or other serosities 

 not spontaneously coagulable produces coagulation, but this occurs, though more slowly, 

 when the serum separated from the coagulated blood is added to these liquids. 



It is more in accordance with our positive knowledge to state that we understand 

 nothing with regard to the cause of coagulation of the blood beyond the tact that plas- 

 mine, when removed from its normal condition in the circulation, decomposes into coat:- 

 ulating fibrin and metalbumen, than to admit the existence of fibrinogen, a ferment, and 

 paraglobuline, all of which may be products of decomposition. 



