COAGULATING PRINCIPLE IN THE BLOOD. 



which lie did by washing the clot in a stream of water, which 

 removed the corpuscles and left a whitish fibrous network. 

 His experiments are set forth in an article in which he at- 

 tempted to show that the so-called polypi of the heart were 

 formed of fibrin, though it was not then called by that name. 

 These observations were soon confirmed by others, and finally 

 Ruysch extracted fibrin from his own blood and the blood 

 of the pig by whipping with a bundle of twigs, and thereby 

 prevented its coagulation. This is the method now most com- 

 monly employed for the separation of fibrin. It then became a 

 question whether this substance existed as a fluid in the liquor 

 sanguinis, or was furnished by the corpuscles after the re- 

 moval of blood from the vessels. This was decided by Hew- 

 son, whose simple and conclusive experiments, published in 

 1TY1, leave no doubt that coagulation of the blood is due to 

 fibrin, and that this principle is entirely distinct from, and 

 independent of, the corpuscles. This observer, taking advan- 

 tage of the property possessed by certain saline substances of 

 preventing the coagulation of the blood, was the first to sepa- 

 rate the liquor sanguinis from the corpuscles. He mixed 

 fresh blood with a little sulphate of soda, which prevented 

 coagulation, and after the mixture had been allowed to stand 

 for a time, the corpuscles gravitated to the bottom of the ves- 

 sel. The clear fluid was then decanted, and diluted with 

 twice its quantity of water, when the fibrin became coagu- 

 lated. 1 Another experiment is still more conclusive ; and aa 

 the credit of having first . separated the corpuscles from the 

 plasma and demonstrated the coagulability of the latter is by 

 some ascribed to Miiller, we will give it in the author's own 

 words : 



" Immediately after killing a dog, I tied lip his jugular 

 veins near the sternum, and hung his head over the edge of 

 the table, so that the parts of the veins where the ligatures 

 were might be higher than his head. I looked at the veins 



1 The Works of William Hewson, F. R. S., Sydenham edition, p. 12. 



