39 



the heart. A little distal to the clamp make an incision in 

 the artery and insert a glass canula and tie it tightly in place. 

 Remove the clamp or ligature and the blood will pass 

 through the canula, and the animal allowed to bleed to 

 death. When the animal is apparently dead, an interesting 

 experiment may be performed by injecting into the artery 

 some normal salt solution of the same temperature as the 

 body and note the reviving effect. 



185. The blood obtained as above directed is to be caught 

 in four different vessels and each portion is to be treated as 

 follows : One portion of the blood is to be defibrinated by 

 immediate whipping with som.e broom straws tied in a small 

 bundle and the fibrin as it collects on the straws is to be 

 saved for future use. The defibrinated blood is also to be 

 reserved for later study. Another portion of the blood is to 

 be collected in a flask and the phenomenon of clotting or 

 coagulation ob,served. Another portion of the fre.sh blood 

 is to be mixed with a saturated solution of sodium sulphate. 

 And still another portion into a solution of potassium oxalate. 



186. Test the reaction of blood by pricking one of the 

 fingers behind the nail. Put a drop of the blood on a piece 

 of ordinary litmus paper which has been soaked in salt solu- 

 tion. The substances on which the alkaline reaction depend 

 will diffuse out in a ring around the drop, while the hemo- 

 globin remains in its original position. 



187. Place a thin layer of defibrinated blood on a glass 

 slide ; try to read printed matter through it. The blood is 

 too opaque and the print cannot be read, the light is reflected 

 from the corpuscles in all directions, and but little passes 

 through. 



188. Place I cc. of defibrinated blood in a test tube and 

 add 5 cc. of distilled water, and warm slightly. Note the 

 change of color by reflected and transmitted light. By re- 

 flected light it is much darker — almost black, but by trans- 

 mitted light it is transparent. This constitutes "laky" 



