The Coagulation Time of the Blood in Man 321 



would have been given. Agglutination is, then, a process which is entirely 

 distinct from coagulation, which it may nevertheless closely simulate. 



No end-point which has yet been suggested can be considered free from 

 fallacy. With the direct methods jBbrin may be inconstant in the time of 

 its appearance or may possibly be sometimes due to purely physical causes, 

 and with the indirect method agglutination may yield appearances usually 

 considered characteristic of coagulation. 



III. Other Methods of estimating the Coagulation Time. 

 Wright's Method. 



Wright (17) published his method in 1893. Since then it has undergone 

 several slight changes. 



In the latest modification (1905) capillary glass tubes are calibrated by 

 an ingenious method. They are filled with blood and placed in water at 

 37" C. At intervals the blood is expressed from one after the other until 

 fibrin is found. 



The method has probably been more widely used than any other. 

 Murphy and Gould (30) compared Wright's (17) and Brodie and 

 Russell's (1) methods. In 15 per cent, of estimations no result was arrived 

 at with Wright's method. Ross (31) gives fourteen cases in which the 

 coagulation time as shown by this method was diminished after calcium. 

 He appears to think that the method is an accurate one. Coleman (32) 

 preferred Brodie and Russell's (1) method. Solis-Cohen (33) made sixty- 

 five observations. He says : " The results obtained were all practically 

 negative, and were, moreover, unsatisfactory." He attributes this to fallacies 

 in connection with the method. Douglass (34) estimated the coagulation 

 time of normal, pregnant, and eclampsic women, but does not express 

 any opinion as to the method. Nias (35) used it to show that strontium 

 as well as calcium diminishes the coagulation time. He says : " In spite of 

 criticisms which have appeared as to the sufficiency of this method, it has 

 proved itself amply adequate for the purpose in hand, very consistent 

 results having been obtained." Hinman and Sladen (36) think that " the 

 pathological differences, and those dependent on technique, in this method, 

 are of about the same relative value, which must confuse the results." 

 Turner (37) made over one thousand observations on normal and epileptic 

 people. His average coagulation time was 2 minutes 40 seconds, and he says 

 that he often found differences of two minutes in tlie results of estimations 

 of blood taken from the same individual by successive punctures. He attri- 

 butes this to rapid variations in the coagulability of the blood and not to 

 any deficiency in the method. 



I made forty-three estimations with the method as described in 1897, 

 with the exception thiit each tube was filled from a separate puncture as is 

 recommended in 1902. In nearly 50 per cent, of them only an approximate 



