BLOOD. 

 FIG. 56. 



189 





OXYHAEMOGLOBIN CRYSTALS FROM BLOOD OF THE NfiCTURUS. 



Reproduced from a micro-photograph furnished by Prof. E. T. Reichert, of the 

 University of Pennsylvania. 1 



iron-containing pigment. The latter body is rapidly transformed 

 into hcematin in the presence of oxygen and this in turn gives place 

 to haematin-hydrochloride or hamin (Figs. 58 and 59, page 198). 

 The pigment of arterial blood is for the most part loosely combined 

 with oxygen and is termed o.r^haemoglobin, whereas the pigment 

 of venous blood is principally haemoglobin (so-called reduced 

 haemoglobin). Oxyhsemoglobin is the oxygen-carrier of the body 

 and belongs to the class of bodies known as respiratory pigments. 

 It is held within the stroma of the erythrocyte. The reduction of 

 oxyhaemoglobin to form haemoglobin (so-called reduced haemo- 

 globin) occurs in the capillaries. Oxyhaemoglobin may be crys- 

 tallized and a specific form of crystal obtained from the blood of 

 each individual species (see Figs. 50 to 56, pages 186 to 189). This 

 fact seems to indicate that there are many varieties of oxyhaemo- 

 globin. The interesting findings of Reichert and Brown are of 

 great value in this connection. These investigators prepared oxy- 

 haemoglobin crystals from over one hundred species of animal and 

 subsequently studied the characteristics of the crystals very min- 

 utely from the standpoint of crystallography. Their findings may 

 prove of importance from the standpoint of heredity and the origin 

 of species. They emphasize the following facts : 



1 The micro-photographs of oxyhaemoglobin (see pages 186-189) and hsemin 

 (see page 198) are reproduced through the courtesy of Professors E. T. 

 Reichert and Amos P. Brown, of the University of Pennsylvania, who are 

 investigating the crystalline forms of biochemic substances. 



