BLOOD AND LYMPH 



269 



This method is more rapid than Teichmann's method and crystals 

 of inorganic chlorides are not formed. In Teichmann's method crystals 

 of sodium chloride often obscure the hemin crystals. 



15. Catalytic Action. To about 10 drops of blood in a test-tube add twice the 

 volume of hydrogen peroxide, without shaking. The mixture. foams. What is 

 the cause of this phenomenon? 



16. Crystallization of Oxyhemoglobin. Reichert's Method. Add to 5 c.c. 

 of the blood of the dog, horse, guinea-pig, or rat, before or after laking, or de- 

 fibrinating, from i to 5 per cent of ammonium oxalate in substance. Place a 

 drop of this oxalated blood on a slide and examine under the microscope. The 

 crystals of oxyhemoglobin will be seen to form at once near the margin of the 

 drop, and in a few minutes the entire drop may be a solid mass of crystals. 

 Compare the crystals with those shown in Figs. 76 to 82, pages 254^0 257. 



FIG. 86. SODIUM CHLORIDE. 



17. Preparation of Hematin. Place 100 c.c. of hemolyzed (laked) f \>\ood in a 

 beaker and add 95 per cent alcohol until precipitation ceases. What bodies are 

 precipitated? Transfer the precipitate to a flask and boil with 95 per cent alcohol 

 previously acidulated with sulphuric acid. Through the action of the acid the 

 hemoglobin is split into hematin and a protein body called globin. Later the 

 "sulphuric acid ester of hematin" is formed, which is soluble in the alcohol. Con- 

 tinue heating until the precipitate is no longer colored, then filter. Partly saturate 

 the nitrate with sodium chloride and warm. In this process the "hydrochloric acid 

 ester of hematin" is formed. Filter and dissolve on the filter paper by sodium 

 carbonate. Save this alkaline solution of hematin and make a spectroscopic ex- 

 amination later after becoming familiar with the use of the spectroscope. How 

 does the spectrum of oxyhemoglobin differ from that of the derived alkali hematin? 



18. Preparation of Thrombin (Howell). 3 Prepare fibrin from pig's blood 

 according to directions given on page 271. Wash the fibrin thoroughly in water 



1 Care should be taken not to add too great an excess of these reagents. 

 'This process insures constancy of temperature and strength of reagents. 

 3 Howell: Am. Jour. PhysioL, 32, 264. 1913. 



