COAGULATION OF THE BLOOD. 265 



solution, not having been precipitated by the addition of sodium chlo- 

 ride. 



According to the other theory (Schmidt), the coagulable fibrine is 

 produced by the union of two previously existing substances, neither 

 of which is coagulable by itself. One of these is termed fibrino-plastic 

 matter, because it has the property of inducing coagulation in a liquid 

 containing the other material. This second material is named fibri- 

 nogen, being considered as more directly the generator of the coagulable 

 fibrine. The plasma of the blood is supposed to contain both these 

 substances, but in very different quantities ; the fibrino-plastic matter 

 being abundant, the fibrinogen comparatively scanty. When the fibri- 

 nogen, accordingly, has all been converted into fibrine and has coag- 

 ulated, a surplus of fibrino-plastic matter still remains in the serum, 

 and may be used to induce coagulation in other liquids which would not 

 coagulate of themselves. This last fact forms the basis of the theory. 

 If the clear serum from coagulated blood be added, at the temperature 

 of the living body, to filtered hydrocele fluid, after some minutes the 

 mixture coagulates into a transparent gelatinous mass, which afterward 

 exudes a colorless serum. Both fibrino-plastic matter and fibrinogen 

 are obtained from the liquids containing them, by dilution with water 

 and by passing though them for a considerable time a continuous stream 

 of carbonic acid. Fibrinogen is also precipitable by the addition of 

 sodium chloride to the point of saturation. 



This theory not having been found sufficient to account for all the 

 phenomena of coagulation, its author has modified it 1 by supposing that, 

 while fibrino-plastic matter and fibrinogen by their combination furnish 

 the material of the coagulable fibrine, they need, in order to effect their 

 union, the influence of a third substance, which does not itself form any 

 part of the fibrine, but which acts as a ferment to excite the combina- 

 tion of the two others. A fluid accordingly may contain both fibrino- 

 plastic matter and fibrinogen, and yet will not coagulate unless the 

 ferment be also present. The ferment is supposed to be generated in 

 the blood only after its withdrawal from the vessels ; and this accounts 

 for its fluid condition while the circulation is going on. 



Neither of the foregoing explanations rests upon complete demonstra- 

 tion. The plasmine of Denis may be, from the first, a mixture of two 

 different substances, both of which are precipitable by sodium chloride 

 from the sodium sulphate solution ; and the union of the tw r o fibrine 

 generators of Schmidt, under the influence of a " ferment," still leaves 

 it quite unknown how or by what causes this ferment is generated when 

 the blood coagulates after removal from the vessels. The only thing 

 which seems absolutely certain is that a substance exists in the blood 

 in small quantity which becomes coagulable by a spontaneous change 

 soon after it is withdrawn from the influences of the circulation. 



If we endeavor to explain why this change and the consequent coagu- 



1 Archiv fur die Gesammte Physiologic, 1872, Band vi. p 413. 

 18 



