Physiology. — "An Objective Method for determininci the Co- 

 atiulatlon-time of Blood.'' By R. J. Wolvius. (Ooinmiinicated 

 by Prof. A. A. Humans van uen Bergh.) 



(Communicated at the meeting of December 23, 1921). 



The usual methods for determining the ooagnlalion-lime of blood 

 aim at detecting the right moment at which the phase of complete 

 solidification of the blood has just set in. 



At fust 1 myself adopted the method suggested by Fonio and 

 Fhank, viz. by observing, wiih strict piecaution, the coagulation of 

 the blood on a watchglass and by noting down the moment at 

 wliich the phase of complete solidification had apparently been 

 reached. However I was always in doubt whether complete solidifi- 

 cation had been accomplished at a certain moment, or whether it 

 had not, so that I always hesitated in tlxing the right moment. 



In this connection Hayfm ^) says: "On sait, en effet, que la solidi- 

 fication dii sang ne se fait pas brusquement, c'est a dire d'un seul 

 coup, a un moment précis. Le phenomène, évolue d'une maniere 

 progressive, a tel point, que pendant une periode relativement assez 

 longue, on reste dans l'hésitation, en se demandant si la prise en gelee 

 est effectuée ou n'est encore qu'imminente." 



What tells most against these methods, is that the degree of 

 solidification has to be determined by subjective observation. I, there- 

 fore, looked for some phenomenon that goes on pari passu with 

 the solidification and admits directly of measurement. I found that 

 phenomenon in tlie turbidity which attends the sailing out of fibrin 

 and consequently decided to measure it. Preliminary experiments 

 had shown that at the very outset of thickening of the blood a 

 clouding commences that increases with the further progress of the 

 thickening and ultimately remains stable as soon as coagulalion 

 has reached its completion. Now, it being my purpose to observe 

 the time in relation to solidification, I might as well ascertain the 

 time taken up by the clouding process. In order to measure this 

 growing turbidity I made use of a new apparatus, the extinction 



^) Hayem, Du Sang, quoted from Marcel Block, La coagulabilité sanguine 

 pag. 22. These, Paris 1914. 



