450 CHEMISTRY OF THE TISSUES. 



bulb, and inject a half per cent, salt solution through it, in the 

 manner directed for artificial circulation in Chap. XVI. 45, 

 till the fluid which issues from the veins is quite colorless. 

 Cut away the muscles close to their attachments, and wash 

 them with half per cent, salt solution cooled to C. When 

 washed, squeeze them tightly together into a ball, and tie them 

 up in a piece of thin linen ; put them into the crucible or tin 

 box. As the muscles of each frog are prepared add them to 

 those in the crucible, and let it remain in the freezing mixture 

 until they are all frozen quite hard. Take a sharp knife and 

 cool it in the freezing mixture; cut the frozen mass of muscle 

 into very thin slices; throw them into a mortar cooled in the 

 same way, and break them up small. Tie them up in a piece 

 of strong linen, and put them into a strong screw-press. As 

 the temperature of the muscle is gradually raised by the 

 warmth of the room to C., the frozen plasma melts and 

 issues from the press. It must be collected in a vessel cooled 

 in ice, and filtered through paper moistened with cold half per 

 cent, salt solution, and collected in a cold beaker. The funnel 

 may be kept cold during filtration by placing it in a double cop- 

 per filtering stand of the form shown in fig. 336, but filled with 

 snow or pounded ice, instead of hot water. As the filters get 

 soon choked, the}' must be frequently renewed. The filtered 

 plasma is a slightly yellowish and opalescent, syriqyy, but not 

 tenacious, fluid. 



Reaction. Its reaction is alkaline, like that of muscle. 



Coagulation of Muscle Plasma. Transfer a little plasma 

 from the beaker to cooled test-tubes and observe the following 

 facts : 



It will coagulate spontaneously when allowed to stand at 

 the temperature of the room, and form a gelatinous clot, which 

 will begin at the sides of the tube, and extend inwards. 



By stirring, a coagulum is obtained, which is flocculent, and 

 not fibrous like the fibrine of blood. 



Heat greatly accelerates its coagulation, and at 40 C. it 

 coagulates almost instantaneously. 



Cold water coagulates it at once, so that the plasma when 

 dropped into it, forms white clastic balls. Cold NaCl solution, 

 of fifteen per cent, also coagulates it, but a solution of five 

 per cent., does not. Dilute hydrochloric acid of ten per cent, 

 coagulates it at once, but dissolves the coagulum, and forms 

 syntoiiin almost immediately. 



* 59. Examination of the Aqueous Extract of 

 Muscle. In order to obtain an aqueous extract of muscle, a 

 dog must be killed by decapitation, and the blood removed 

 from the vessels of the lower extremities by artificial circula; 

 tion. For this purpose open the abdomen quickly, and insert 

 a canula in the aorta. Inject ten per cent. NaCl solution into 



