40 



PRACTICAL PHYSIOLOGY. 



[V. 



(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. 



(r.) To 2 CO. of salted plasma, prepared as in Lesson V. 13 

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

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

 pared by the demonstrator = coagulation. 



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

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

 at 40° C. The CaCl2 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 aU. 

 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 D add serum. Keep C 

 and D at 40° C. They coagu- 

 lated rapidly, because of the 

 abimdance 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 Sulphunc Acid. b. Glass bell-jar, cover- „ „„„f, f „i„^v„i „^n„ ,4. 4.v„ „^^;^„o 

 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- 

 teid.s are rendered insoluble. Dry the precipitate at 35° C, and afterwards 

 over suli>huric 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 

 for salts and sugar. 



Coagulum coloured brown by ha 

 matin. 



