58 



222. 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 some 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 collect- 

 ed in a flask and the phenomenon of clotting or coagulation 

 observed. Another portion of the fresh blood is to be mixed 

 with an equal volume of saturated solution of sodium sulphate. 

 And still another portion into a solution of potassium oxalate 

 in the proportion of 1 of the oxalate to 4 of the blood. 



223. 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. 



224. 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. 



225. Place 1 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" 

 blood due to the withdrawal of the hemoglobin from the red 

 corpuscles into the water. Test the transparency by looking 

 at some printed matter through this blood as in 224. 



226. To 2 cc. of defibrinated blood in a test tube add 5 

 volumes of a 10% solution of sodium chloride. It changes to 

 a very bright, florid, brick-red color. Compare its color with 

 No. 225. ' 



i 227. Place a watery solution of defibrinated blood in a 

 dialyzer or oarchment tube, and suspend in a vessel of distilled 

 watea^ ^icRer sever^ hours note that no hemoglobin has 

 passed into the water. Test the diffusate for chlorides with 

 silver nitrate and nitric acid. Hemoglobin does not dialyze, 

 although it is crystallizable. 



