BY DR. BURDON-SANDERSOX. 183 



yielded by the plasma is much less (so to speak) than it ought 

 to be, i. e., much less than that yielded by a corresponding 

 quantity of blood. This fact, taken in connection with the 

 result of our experiment, leads us to regard it as probable that 

 In circulating blood, the liquor sanguinis contains less of the 

 fibrin factors than it does immediately after its removal from 

 the body. If this inference is correct, there can be little doubt 

 that it somehow or other, in leaving the living vessel, acquires 

 fresh properties of coagulation from its formed elements. 

 Heynsius believes that the colored blood disks are alone con- 

 cerned in this action, and attributes it to the discharge into 

 the plasma of certain of their constituents. His results are,' 

 however, quite as consistent with the belief that the colorless 

 elements are the chief agents, in favor of which several facts 

 may be demonstrated. Vaccine and blister fluid are both co- 

 agulable ; they contain no colored blood corpuscles, but always 

 many colorless corpuscles. If the process of coagulation is 

 watched in either of these liquids under the microscope, it is 

 seen, not merely that it begins from these elements, but that 

 it occurs nowhere in the liquid excepting where they are pre- 

 sent. Again, if a ligature is drawn through a vein in which 

 blood is circulating, as e. g., through the external jugular of 

 a rabbit or guineapig, and allowed to remain there for a time, 

 and then removed and examined microscopically, it is found 

 that the threads of the ligature are crowded, and its surface 

 encrusted, with colorless corpuscles. These bodies are held 

 together by fibrin, which appears to grow from their surface 

 into the blood-stream. 



SECTION II. CONDITIONS WHICH AFFECT THE COAGULATION OF THE 



BLOOD. 



Although the circulating blood contains either in its colored 

 corpuscles or plasma both the fibrin factors, i. e., the imme- 

 diate principles necessary for its coagulation, it does not co- 

 agulate. In other words, the blood, so long as it forms part of 

 the normal living body, contains no fibrin. This remarkable 

 fact is dependent on the maintenance in the corpuscles of those 

 chemical changes which constitute their life. And inasmuch 

 as these changes cannot continue in the absence of the physical 

 and chemical conditions to which the blood is subjected, so 

 long as it is contained in healthy bloodvessels, any derange- 

 ment of those conditions leads to the formation of a clot. It 

 can be proved experimentally (1) That blood does not coagu- 

 late in the living heart or in a living bloodvessel, even when 

 the circulation is arrested ; (2) That although normal blood 

 ordinarily coagulates as soon as it is withdrawn from the body, 

 there are certain circumstances under which the act of coagu- 



