316 



Addis 



This is in direct contradiction to the conclusions of the originators of 

 some of the methods, who, while admitting the importance of large varia- 

 tions, believe that slight ones have so little effect that they may, for 

 practical purposes, be neglected. No one of them, however, has brought 

 forward any experimental proof of this assumption. 



The extraordinaiy variations in the coagulation times obtained by the 

 use of their methods are to a great extent due to variations of the 

 temperature. This is illustrated in the following three charts: — - 



Figure 3 is a chart showing consecutive coagulation times, taken in 



£-3 a 





PiQ. 8. — Diagram showing the coagulation time 

 (thick line) and variations of room tempera- 

 ture (thin line) in an experiment upon the 

 blood of a normal person taken at different 

 periods of the day (Dec. 22), and estimated 

 by M'Gowan's luethod. 



12 1 2 3 4 5 6 7 8 9 10 11 Hours of 



the day. 



a room in which the temperature never varied so much as to make the 

 room noticeably cold or hot. 



M'Gowan's method (16) was used. The originator of this method 

 does not think that accurate results can be gained by the use of the 

 method without the addition of some means of keeping the temperature 

 constant. 



In this case, however, the tubes were simply left to acquire the 

 temperature of their surroundings. 



The amount of variation in the time is very great, and the curve of 

 coagulation, though complicated by experimental error due to other 

 causes, is seen roughly to run in the opposite direction to the curve of 

 temperature. 



In the next chart (fig. 4) the times were taken by the same method, 

 modified by keeping the tubes in an apparatus I had constructed in order 



