The Coagulation Time of the Blood in Man 323 



Burker found that his results were untrustworthy unless he diluted 

 the blood with water. The reason for this may be that the mechanical 

 production of fibrin is prevented. Further, the end-point is not a good 

 one to select, for sometimes a thread and sometimes a large mass of fibrin 

 is demonstrated. In the latter case an earlier stage of coagulation has 

 been missed. 



Sabraz^s' Method. 



This method depends on the fact that when blood coagulates in capillary 

 glass tubes a fine thread of fibrin can be demonstrated when the tube is 

 broken and the ends drawn slowly apart. The rest of the apparatus is 

 intended to keep the tubes at a constant temperature. It consists of two 

 superimposed glass boxes. The lower box contains warm water in winter 

 and ice in summer. In the upper box the tubes are placed in close proximity 

 to a thermometer. 



The end-point, as will be shown in speaking of the next method, is a 

 good one, but the method is not accurate, because it is impossible to main- 

 tain the temperature of the tubes constant throughout the experiment. A 

 tube is taken out and broken across every half minute. To do so it is 

 necessary to remove the lid, and the temperature inside at once tends to 

 rise or fall according to the temperature of the air in the room. For this 

 reason I found it was quite impossible to maintain anything approaching 

 a constant temperature, and as a consequence the results obtained were 

 very variable. Geneuil (38) has used this method, and has obtained very 

 variable results in different pathological conditions. 



M'Gowan's Method. 



Glass tubes 1*5 mm. in diameter and 7 inches long are partially filled 

 with blood. Portions are broken off every half minute until a thread of 

 fibrin is seen. 



The author believes that for clinical work variations of temperature 

 between 15° C. and 20° C. may be neglected, though he admits that to 

 obtain accurate results some method of keeping the temperature constant 

 would be necessary. He also suggests that in clinical work the coagulation 

 time of the patient should be compared with the coagulation time of the 

 observer's blood, which might be assumed to represent the normal. 



In testing this method it was at once apparent that it was useless even 

 for rough clinical work unless some means were employed of keeping the 

 temperature of the tubes constant. Thus when two tubes, both filled from 

 the same drop of blood at the same moment, were kept at 15'5° C. and 

 19° C. respectively, the coagulation times were 9 minutes 30 seconds and 5 

 minutes 45 seconds. I have had an apparatus constructed which is fairly 

 successful in maintaining a constant temperature, and with this addition 

 I regard the method as more trustworthy than any of those hitherto used. 



In order to find whether the end-point adopted was to be depended on, 

 VOL. I., NO. 4. — 1908. 22 



