321 

 329 



THE COAGULATION TIME OF THE BLOOD IN MAN. By T. Addis. 

 (From the Physiology Laboratory, University of Edinburgh.) (With 

 five figures in the text and two Plates.) 



(Received for publication 1st August 1908.) 

 CONTENTS. 



PAGK 



I. A New Method of estimating the Coagulation Time of the Blood 305 



II. The Conditions which are essential for thb Accurate Estimation 



OF the Coagulation Time ...... 314 



III. A Review of other Methods ..... 



IV. The Effect of Variations of Temperature on the Coagulation 



Time •••..... 



V. The Absence of Diurnal Variation in thu Coagulation Time . 330 



VI. The Effect of the Administration of Calcium and Citric Acid by 



the Mouth on the Coagulation Time .... 331 



VII. Conclusions ......... 331 



I. A New Method of estimating the Coagulation Time. 

 When a current of oil streams against the edge of a drop of blood sus- 

 pended in oil, a continuous smooth flow of the corpuscles is induced, 

 although the drop as a whole does not rotate. Under the microscope this 

 flow will be seen to cease quite suddenly after a certain time has elapsed. 

 This is due to the occurrence of coagulation in the drop. 



The method is a modification of Brodie and Russell's method (1). In- 

 stead of intermittent jets of air at an unknown and variable temperature, a 

 continuous stream of oil at a known and constant temperature is used. The 

 end point also is entirely different. 



The whole apparatus is placed on a small table to which an upright has 

 been attached (see Plates at end of article). 



A reservoir (P) of filtered mineral oil such as is used for burning in 

 lamps is hung from the upright by a cord passing through a pulley so 

 that its height can be varied at will. Any vessel will do for a reservoir so 

 long as it contains a sufficiently large surface of oil, in order that the 

 amount which runs out during an observation may not materially affect 

 the pressure of the flow of oil by altering its level in the reservoir. 



The oil is conducted from the reservoir through six feet of flexible metal 

 asbestos-lined quarter-inch tubing (p). The usual flexible metal tubing 

 should not be used, because it is packed with rubber which soon rots under 

 the influence of the oil. 



