BLOOD. 1 99 



hsemin crystals dissolve the sodium chloride crystals by running 

 a drop of water under the cover slip. 



(c) v. Zeynek and Nencki's Method. To 10 c.c. of defibrinated 

 blood add acetone until no more precipitate forms. Filter off the 

 precipitated protein and extract it with 10 c.c. of acetone made 

 acid with 2-3 drops of hydrochloric acid. Place a drop of the 

 resulting colored extract on a slide, immediately place a cover glass 

 in position and examine under the microscope. Upon the evapora- 

 tion of the acetone, crystals of haemin will form. Larger crystals 

 may be obtained by evaporating the acetone extract about one- 

 half, transferring it to a stoppered vessel and allowing it to remain 

 over night. 



(d) Schalfijew's Method. Place 20 c.c. of glacial acetic acid 

 in a small beaker and heat to 80 C. Add 5 c.c. of strained defibri- 

 nated blood, again bring the temperature to 80 C., remove the 

 flame and allow the mixture to cool. Examine the crystals under 

 the microscope and compare them with those reproduced in Figs. 

 58 and 59, page 198. 



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? 



1 6. Preparation of Haematin. Place 100 c.c. of laked blood 

 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 sul- 

 phuric acid. Through the action of the acid the haemoglobin is 

 split into hsematin and a protein body called globin. Later the 

 "sulphuric acid ester of hsematin" is formed, which is soluble in 

 the alcohol. Continue heating until the precipitate is no longer 

 colored, then filter. Partly saturate the filtrate with sodium chlo- 

 ride and warm. In this process the " hydrochloric acid ester of 

 hsematin" is formed. Filter and dissolve on the filter paper by 

 sodium carbonate. Save this alkaline solution of haematin and 

 make a spectroscopic examination later after becoming familiar 

 with the use of the spectroscope. How does the spectrum of oxy- 

 haemoglobin differ from that of the derived alkali harnatin? 



17. Variation in Size of Erythrocytes. Prepare two small 

 funnels with filter papers such as are used in quantitative analysis. 

 Moisten each paper with normal (isotonic) salt solution. Into one 

 funnel introduce a small amount of defibrinated ox blood and into 

 the other funnel allow blood to drop directly from a decapitated 



