40 



PRACTICAL PHYSIOLOGY. 



(b.) To 5 cc. of hydrocele fluid add some solution of fibrin- 

 ferment, and keep in a water-bath at 40 C.. coagulation takes 

 place. 



(c.) To 2 co. of salted plasma, prepared as in Lesson V. 13 

 (which is known to clot slowly on the addition of water), add 10 

 volumes, i.e., 20 cc. of a watery solution of fibrin-ferni3nt, pre- 

 pared by the demonstrator = coagulation. 



(d.) Add to oxalate-plasma (Lesson Y. 14) a few drops of a 2 

 per cent, calcium chloride solution. Jt coagulates, and more quickly 

 at 40 C. The CaCl 2 supplies the calcium necessary for the forma- 

 tion of fibrin. 



(e.) Effect of Temperature on Coagulation. Dilute sodium 

 sulphate plasma with 10 volumes of water, and place some in test- 

 tubes A, B, C, D. 



A clots slowly or not at all. 

 Place B in water-bath at 40 

 C. It clots more quickly. 



To C add a small quantity 

 of fibrin-ferment (p. 40), dis 

 solved in a little calcium 

 chloride. 



To I) add serum. Keep C 

 and D at 40 C. They coagu- 

 lated rapidly, because of the 

 abundance of fibrin-ferment. 



22. Preparation of Fibrin-Fer- 

 ment. It must be kept in stock. 

 FIG. i6.-Exsiccator for Drying a Precipitate Precipitate blood-serum with a large 

 over Sulphuric Acid. b. Gla*s bell-jar, cover- ' , -, , , ,-, , ,, 



ing vessel with sulphuric acid (c), and support excess of alcohol, collect the copious 

 (d) for the deposit or precipitate. precipitate, consisting of the pro- 



teids and fibrin-ferment. Cover it 



with absolute alcohol, and allow it to stand at least a month, when the pro- 

 teids are rendered insoluble. Dry the precipitate at 35 C., and afterwards 

 over sulphuric acid (fig. 16). Keep it as a dry powder in a well -stoppered 

 bottle. When a solution is required, extract some of the dry powder with 100 

 volumes of water ; filter. The filtrate contains the ferment. 



23. Salts and Sugar of Serum. The usual salts may be tested 

 for directly with serum diluted with water or the following method 

 may be adopted : 



Dilute blood and boil it ; filter. 



Colourless filtrate, which can be tested Coagulum coloured brown by hae- 

 for salts and sugar. matin. 



