THE BLOOD. 69 



of coagulation by the disintegration of the colorless (and possibly of the 

 colored) corpuscles. This supposition is certainly plausible, and if it be 

 a true one, it must be assumed either that the living blood-vessels exert 

 a restraining influence upon the disintegration of the corpuscles in suffi- 

 cient numbers to form a clot, or that they render inert any small amount 

 of fibrin ferment which may have been set free by the disintegration of 

 a few corpuscles; as it is certain, firstly, that corpuscles of all kinds must 

 from time to time disintegrate in the blood without causing it to clot; 

 and, secondly, that shed and defibrinated blood which contains blood 

 corpuscles, broken down and disintegrated, will not, when injected into 

 the vessels of an animal, under ordinary conditions, produce clotting. 

 There must be a distinct difference, therefore, if only in amount, between 

 the normal disintegration of a few colorless corpuscles in the living un- 

 injured blood-vessels and the abnormal disintegration of a large number 

 which occurs whenever the blood is shed without suitable precaution, or 

 when coagulation is unrestrained by the neighborhood of the living un- 

 injured blood-vessels. 



The explanation of the clotting of blood which has been given in the 

 preceding pages and which depends chiefly upon the researches of Alex. 

 Schmidt and Hammersten, supposes that it is one of the fermentative 

 actions, so many of which are believed to go on in the living body. Wool- 

 dridge ably contests this view of the process. His laborious researches 

 have led him to the belief that coagulation of the blood is a vital pro- 

 cess, or rather that it is the last act of vitality displayed by blood plasma, 

 which he considers to be during life, living protoplasm. Some of the 

 results of his experiments may with advantage be here mentioned, as 

 they correct and amplify the information as to blood-clotting which has 

 been hitherto given and received. Firstly, he has shown that plasma 

 itself contains everything that is necessary for coagulation. Peptone 

 plasma obtained by injecting a solution of peptone into the veins of an 

 animal and bleeding it immediately afterwards was experimented with. 

 The whole of the corpuscular elements were removed by repeated treat- 

 ment with a centrifugal machine. The plasma thus obtained was shown 

 to clot by the use of some simple mechanical means, e.g., filtering 

 through a clay cell, or through filter paper, or on neutralization with 

 acetic acid, or carbonic acid, or by dilution with water or saline solution. 

 Thus it would appear that if the colorless blood-corpuscles aid coagula- 

 tion, their influence is only secondary. 



Secondly, he has shown that the important precursor of clotting in 

 this peptone plasma may be separated from it, as a precipitate, if the 

 plasma be kept in ice for some time, and that after its removal the 

 plasma contains only a little fibrinogen capable of clotting by the action 

 of fibrin ferment. If the plasma be diluted with water or slightly acid- 

 ulated, however, the fibrin ferment is able to produce a complete 

 clotting. 



In peptone plasma, Wooldridge states that three coagulable bodies 

 exist, which he calls A, B, and fibrinogen, and which are closely 

 allied to one another. C-fibrinogen is identical with the body which 

 has been hitherto described as fibrinogen, is present in very small amount, 



