200 THE INCOME OF ENERGY 



of ox, dog, or horse, by adding 15-20 parts strong 

 alcohol. After at least fourteen days, filter, dry 

 the moist residue over sulphuric acid, pulverize 

 the dried substance, stir it with water (twice the 

 volume of the serum originally taken) and after 

 allowing sufficient time for solution, filter. The 

 filtrate contains the fibrin ferment. 1 



Gamgee's Method. Allow freshly prepared fi- 

 brin (obtained by washing a blood clot free from 

 corpuscles) to stand three days in 8.0 per cent 

 solution of sodium chloride. Filter. 2 



The filtrate is rich in fibrin ferment. 



Extraction of Fibrinogen -- Receive three 

 volumes of blood directly from an artery into 

 one volume of saturated solution of magnesium 

 sulphate, which will prevent the blood from 

 clotting. Separate the corpuscles from the liquid 

 plasma by the centrifugal machine. Add to the 

 plasma an equal volume of saturated solution of 

 sodium chloride. Flakes of fibrinogen will be 

 precipitated. FiLer as quicklv as possible, for 

 that purpose dividing the liquid among several 

 funnels each with a folded filter paper. Press 

 the filter papers containing the residue between 

 fresh filter paper, in order to remove the adherent 



1 Schmidt : Archiv fur die gesammte Physiologic, 1872, vi, 

 p. 457. 



2 Ganigee : Journal of physiology, 1879, ii, p. 151. 



