BLOOD AND LYMPH 253 



millimeter. The number of erythrocytes varies greatly under different 

 conditions. For instance, the number may be increased after the trans- 

 fusion of blood of the same species of animals; by residing in a high 

 altitude; or as a result of strenuous physical exercise continued over a 

 short period of time. An increase is also noted in starvation; after 

 partaking of food; after cold or hot baths; after massage, in partial 

 asphyxia, and after fright, as well as after the administration of certain 

 drugs and accompanying certain diseases, such as cholera, diarrhea, 

 dysentery and yellow atrophy of the liver. A decrease in the number 

 occurs in the different forms of anemia. The number has been 

 known to increase to 7,040,000 per cubic millimeter as a result of 

 physical exercise, while 11,000,000 per cubic millimeter have been 

 noted in cases of polycythemia and increases nearly as great in cyanosis. 

 The number has been known to decrease to 500,000 per cubic milli- 

 meter or lower in pernicious anemia. 



Erythrocytes possess the property, when properly treated, of 

 " clumping" together in masses and precipitating, producing so-called 

 agglutination. Cells other than erythrocytes (e.g., bacteria) possess 

 this property. When spoken of in connection with the blood such 

 action is termed hemagglutination. A substance which will bring about 

 hemagglutination is said to contain hemagglutinins. These hem- 

 agglutinins are particularly abundant in the vegetable kingdom. 1 For 

 a demonstration of hemagglutination see page 265. 



Oxyhemoglobin, the coloring matter of the blood, is a conjugated 

 protein. Through treatment with hydrochloric acid it may be split into 

 a protein body called globin, and hemochromogen, an iron-containing 

 pigment. The latter body is rapidly transformed into hematin in the 

 presence of oxygen, and this in turn gives place to hematin-hydrochlor- 

 ide or hemin (Figs. 84 and 85, page 268). The pigment of arterial blood 

 is for the most part loosely combined with oxygen and is termed oxy- 

 hemoglobin, whereas the pigment of venous blood is principally hemo- 

 globin (so-called reduced hemoglobin). Oxyhemoglobin is the oxygen 

 carrier of the body and belongs to the class of bodies known as respira- 

 tory pigments. It is held within the stroma of the erythrocyte. The re- 

 duction of Oxyhemoglobin to form hemoglobin (so-called reduced hemo- 

 globin) occurs in the capillaries. Oxyhemoglobin may be crystallized 

 and a specific form of crystal obtained from the blood of each individual 

 species (see Figs. 76 to 82, pages 254 to 257). This fact seems to indi- 

 cate that there are many varieties of Oxyhemoglobin. The interesting 

 findings of Reichert and Brown are of great value in this connection. 

 These investigators prepared Oxyhemoglobin crystals from the blood 



1 Mendel: Archivio di fisiologia, 7, 168, 1909; also Schneider: Journal of Biological 

 Chem., n, 47, 1912. 



