The C'o.i^julation Time of the Blood in Man 381 



changes in coaoulability, were really due to variations in tlu' surroundinof 

 temperature. 



With tlie method described in Section I., in which tenijxTatuvt' xaiiation.-, 

 are entirely excluded, the coagulation time was found to be lemarkably 

 constant at all times of the day and night. The slight variati<jns which 

 occur are irregular and are due to experimental error. 



For twenty days the coagulation time of my own l)lood and that of 

 certain other persons was taken everj' hour or two, and in no one of the 

 charts prepared from these observations do any variations occur which are 

 outside the limit of experimental erroi-. 



The following figures are the averages of more than three hundred 

 observations taken at diffVrent hours of the dav, at a tempt rature of 

 ISTy" C. :— 



Time of day. A\ iia^'e coagulation time, 

 mill. sec. 



The assimilation of food has been described as a cause of variation in 

 the coagulation time by Biirker (21), Coleman (32), and others. 



The coagulation time was estimated on ten different occasions both 

 before and after breakfast. The average time before food was 7 minutes 

 47 seconds, and the average after was 7 minutes 46 seconds. 



VI The Effect of the Administration of Calcium and Citric 

 Acid by the Mouth on the Coagulation Time. 



The details of work done in this connection will be published elsewhere 

 (42\ The general conclusion arrived at is that calcium and citric acid, when 

 given by the mouth, have no influence on the coagulation time. This is 

 not due to entire non-absorption, but to the fact that the change they 

 produce on the calcium content of the blood is so slight that no appreciable 

 effect is produced. 



VII. Conclusions. 



1. There are four conditions which must be fulfilled by any method 

 which is to yield results which can be relied upon, (a) There must be a 

 uniform method of obtaining the blood, (b) The temperature must be 

 the same during each experiment. (c) The amount of contact with 

 foreign bodies must be always the same. (d) The end-point must be 



