330 Addis 



When the results are plotted out so as to form a curve it can be seen 

 that the effect of variation of temperature is much more marked at the 

 lower temperatures. Thus from 325 to 7 25° C. there is a diminution of 

 the time of over 30 minutes, while from 725 to 1225'' C. there is a difference 

 of only 16^ minutes. From 12-25° C. there is at first a fall of about 2 minutes 

 for every degree of temperature, but this diminishes until at about 28° C. 

 it is only half a minute. From this point the periods beoome very slowly 

 shorter until 36° C. is reached, when the blood coagulates in 1 minute 

 25 seconds. Above 36° C. they begin to increase slowly up to 51-5° C, at 

 which temperature the blood takes 5^ minute.s to coagulate. 



At temperatures below 10° C. a tendency for the red blood corpuscles 

 to become agglutinated became apparent, so that twice the usual pressure 

 of oil was necessary to keep the corpuscles flowing separately from 

 each other. 



Above 40° C. the same phenomenon occurred, and became progressively 

 more marked as the temperature rose. Above 5 15 a regular flow could 

 not be induced. At 535° C. there was no evidence of any clot after 

 6 minutes, but the movement was very slow and irregular. At 56° C, at 

 which temperature fibrinogen would be heat-coagulated, the blood was not 

 moved even by the highest pressures, but collected in whorls and clumps 

 of agglutinated corpuscles. No change was apparent in their shape or size. 



V. The Absence of Diurnal Variation in the Coagulation Time. 



Vierordt (27) tried to determine whether there were any regular diurnal 

 fluctuations in the coagulation, time but was unable to show directly that 

 these existed, although he found differences in the averages of the observa- 

 tions taken at different periods of the day. 



Btirker (21) has stated, as a result of two-hourly observations for three 

 days, that the coagulation time is longest in the morning and diminishes 

 until it reaches its lowest point about 2 o'clock p.m., after which it rises 

 again. This statement is not. however, quite borne out by his figures. 



Coleman (32) says that the time is shortest in the morning and longest 

 in the early hours of the afternoon. 



Hinman and vSladen (36) do not come to any definite conclusion, but 

 are inclined to think that the time is longest in the morning. 



The fact that diurnal variations exist has never been called in question, 

 simply because it was often found that different coagulation times were 

 obtained at different periods of the day. This was attributed to time 

 differences in the coagulability of the blood instead of deficiencies in the 

 technique of the method which was used. 



When working with M'Gowan's (16) method I noticed that the more 

 temperature variations were excluded the smaller was the amount of 

 difierence in the coagulation times, and that fluctuations in the coagulation 

 curves, which I had formerly considered to be indicative of intrinsic 



