THE BLOOD. 23 



(b.) Place 15 cc. of the salted plasma separated by means 

 of the centrifugal apparatus in a tall, narrow, cylindrical, 

 stoppered glass. Add powdered sodic chloride, and shake 

 the whole vigorously, when a white flocculent precipitate is 

 thrown down. Allow the precipitate to subside. Decant 

 off the supernatant fluid and the salt solution. Filter 

 through a filter, moistened with a saturated solution of sodic 

 chloride, and wash the precipitate on the filter with saturated 

 solution of sodic chloride. This is the plasmine of Denis. 

 Scrape the washed precipitate off the filter by means of a 

 knife. 



Dissolve it in a small quantity of distilled water, and filter 

 quickly. The filtrate if set aside will clot after a time. It 

 is better to do the several operations rapidly to ensure 

 success, but I have frequently found coagulation occur 

 when the plasmine was not dissolved in water until many 

 hours after it was deposited. 



11. Defibrinated Blood. In the slaughter-house allow blood 

 to run from an animal into a vessel, and with a bundle of twigs 

 beat or whip the blood steadily for some time. Fine white 

 fibres of fibrin collect on the twigs, while the blood remains 

 fluid. This is defibrinated blood, and although set aside for any 

 length of time, it does not coagulate spontaneously. 



(a.) With a few thin twigs, or the barbed end of a quill, 

 beat some freshly-shed blood, and observe the fibrin sticking 

 to the twigs. Wash it. 



12. I. Fibrin. Take the twigs coated with fibrin of the pre- 

 vious experiment. Wash away the colouring-matter with a 

 stream of water until the fibrin becomes quite white. 



(a.) Study its physical properties: it is a white, fibrous, 

 highly-elastic substance. Stretch some fibres to observe 

 their extensibility ; on freeing them, they regain their shape, 

 showing their elasticity. 



(b.) Place a few fibrils in absolute alcohol to rob them of 

 water, when they become brittle, and lose their elasticity. 



(c.) Place a flake in a test-tube with some 0-2 per cent, 

 hydrochloric acid in the cold. It swells up and becomes 

 clear and transparent, but does not dissolve. 



