312 



Addis 



The 'first appearance of a streak of clot has been found too variable to 

 use as an end-point. 



In the following columns the times given by the second stage^ and by 

 the third, are compared : — 



The average time taken to arrive at stage II. was 7 minutes 49 seconds, 

 and to arrive at stage III. was 8 minutes 41 seconds. 



When the second stage was taken as the end-point, the average variation 

 from the mean was 20 seconds ; when the third stage was adopted, it was 

 27 seconds. 



The second stage lias, therefore, always been observed as the end-point. 

 It is better than the third also because it is difficult to say when the 

 stoppage is to be considered " practically complete." The positively complete 

 cessation of flow is very variable, since a few clumps of corpu.scles .«;Ometinies 

 wander slowly round for a considerable time. 



But the second stage also is not always quite definite, though it mucli 

 more often is so. The main mass of the blood usually stops moving at a 

 definite moment, and in the next second or two a clear laminated clot stands 

 out. But sometimes this develops slowly, and in these cases it is impos- 

 sible to be quite accurate, for judgment is necessary to decide when the 

 clotting is distinct enough to be considered as the end-point. The amount 

 of possible error is, however, strictly limited, because the fiow always stops 

 completely within, at most, 90 seconds after the commencement of the 

 second stage. 



Now and again the main body of the blood ceases to flow without the 

 clear appearance of any clot. 



This, I think, is usually due to the agglutination of the blood not 



