The Coagulation Time of the Blood in Man 31.'> 



having been properly overcome at the beginning. The time obtained in 

 these cases is, as it happens, usually approximate to the mean time. 



Variations in the agglutination of the red blood corpuscles of healthy 

 people, as shown by differences in the pressure of oil needed to set the 

 corpuscles Mowing each one separately from the other, are slight, and have 

 never given rise to serious error or difficulty. 



J found, however, when I came to apply the method to jjathological 

 cases, that this agglutination of corpuscles was greatly increased in 

 disease. 



In one iiisfance this was so marked that no flow could be started in the 

 blood even after the pressure had been raised high enough to drive part 

 of the drop off the end of the cone. I cannot at present say in what class 

 of cases this condition is most marked, for I have made but few observa- 

 tions on pathological conditions ; it was, however, present in a varying 

 degree even in some convalescent patients. 



In one or two instances no accurate estimation of the coagulability could 

 be made, because even the highest pressures failed to produce a smooth and 

 even flow, the corpuscles remained sticking together in clumps, and flowed 

 slowly and with jerks. 



It is interesting to note that Fleming (4) has found, in connection with 

 work on the opsonic method, that in 90 per cent, of patients at St Mary's 

 Hospital the red blood corpuscles are agglutinated by their own serum. 

 This condition is very rare in health. Hek toen (5) says that auto-agglutinin 

 is very seldom if ever demonstrable in vitro in the blood of healthy people. 

 In disease the agglutination is possibly due to the action of bacterial 

 haem-agglutinins, for it has been shown by Pearce and Winne (6) that 

 certain bacteria produce a substance which agglutinates red blood corpuscles 

 in vitro, and which when injected into animals leads to the formation of 

 thrombi composed of agglutinated corpuscles. In 1873 Hueter (8) showed 

 that certain thrombi in infectious diseases were due not to coagulation but 

 to agglutination. Flexner (f)) confirmed this, and reproduced it experi- 

 mentally by the injection of bacterial filtrates. Boxmeyer (10), Kraus 

 a)id Ludwig (11), Volk and Lipschiitz (^12), Kayser (13), and Eisenberg 

 (14) have also demonstrated the action of bacterial hami-agglutinins. 



In cases in which this increased U'udeiicy to agglutination has developed, 

 the flow of the corpuscles is hindered and the estimation of the coagulation 

 time may be impossible. 



In many pathological conditions, therefore, tlie method is inapplicable, 

 though in these cases it may be of value in showing the degree of auto- 

 agglutination which is present. 



Unless otherwise stated, the coagulation times given in the following 

 sections were taken by this method at a temperature of 185" C. 



