242 



THE RED BLOOD CORPUSCLES. 



[CH. X 



The method of formation of certain of the derivatives 

 of haemoglobin can be represented as follows : 



METHAEMOGLOB1N 



Dilute , ALKALINE 



Alkalies HAEMATIN + Globin 



HAEMOGLOBIN ^^^ HAEMOCHROMOGEN 



Jron+ ACID HAEMATOPORPHYR1N 



ALKALINE HAEMATOPORPHYRIN 



289. Crystallisation of oxyhaemoglobin (Rapid method). To 



a few cc. of defibrinated dog's blood in a test-tube add ether, drop 

 by drop, till the blood is completely laked. Add to the blood a 

 pinch of finely powdered ammonium oxalate ; allow the salt to dis- 

 solve by gentle shaking, and let the tube stand. Crystals of oxy- 

 haemoglobin separate out, especially if the solution is cooled to 

 o C. by means of ice. Examine them microscopically, and note 

 that they are in the form of thin rhombic prisms. 



Make a drawing of the crystals. 



NOTE. This experiment does not always succeed as described. If the 

 blood fails to crystallise out in an hour, place a drop on a slide, spread it out to 

 form a thin layer and leave it for five minutes ; cover with a slip and note the 

 crystals of oxyhaemoglobin that form at the edges. 



