BLOOD. 



VII. HAEMOGLOBIN AND ITS DERIVATIVES. 



1. Haemoglobin Crystals. Shake up some defibrinated 

 blood with CO 2 gas; add ether, slowly, until the blood has become 

 laked. Set in the cold for several days. Part of the haemoglobin 

 will have crystallized out and may be removed with a pipette and 

 examined under the microscope. 



Haemoglobin of different animals crystallizes with varying facil- 

 ity. The haemoglobin of man and of the herbivorous animals is 

 very soluble and crystallizes with great difficulty. That of the rat 

 and guinea-pig is much less soluble and therefore crystals are 

 easily obtained. 



With the blood of the rat, all that is needed is to take a drop of 

 fresh blood, place it on the centre of a glass slide, add a drop 

 of distilled water, and when the edges begin to dry, cover 

 with a cover slip and examine under the microscope (Funke's 

 method). 



2. Hsematin. Haemoglobin is composed of a pigment united 

 with a proteid body which has erroneously, according to Schae- 

 fer, been called globin. The pigment may be separated from the 

 proteid in the following manner: 



To some defibrinated blood in a test tube add a few drops of 

 KOH solution and heat gently. The solution assumes a greenish- 

 red color. Now carefully neutralize by adding dilute HC1 until 

 the haematin is thrown down as a brownish precipitate. 



The same result is attained through treatment of the blood with 

 an acid and then neutralizing with an alkali. Haemoglobin is 

 therefore decomposed by acids and alkalies into pigment and 

 albuminous compounds. All the iron is contained in the hae- 

 matin. 



3. Haematin Hydrochloric! (haemin). Place a very small 

 drop of blood upon a glass slide. Mix with this a drop of glacial 

 acetic acid. Heat to the boiling point over a small flame. Allow 

 the fluid to evaporate and examine the residue under the micro- 

 scope. Tiny reddish-brown prismatic crystals will be seen. These 



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