THE RED BLOOD CORPUSCLES 



175 



Variations in Shape. — Although it is claimed by Schultze^ that the 

 erythrocytes of the chick possess active motion, it seems that the red 

 blood cells of the mammals remain perfectly passive as long as the 

 fluid in which they are kept, retains its normal character. But 

 their form may be changed at any time by varying the temperature or 

 the carbon dioxid content of the medium, or by permitting an elec- 

 trical current to pass through them. Most generally, they react to 



Fig. 100. — Human Blood-Corpuscles Arranged in Rouleaux. (Funke.) 



these changes by increasing their volume. Moreover, Cavazzani 

 has shown that if blood is collected in an isotonic or hypotonic solution 

 of sodium chlorid to which potassium ferrocyanid has been added, the 

 red corpuscles of man and other animals send out delicate protoplasmic 

 processes, the rapid motion of which enables them to move about 

 from place to place. If a drop of cocain hydrochlorid is then added to 

 this solution, these filaments are retracted within a few moments. 



Fig. 101. — PoiKiLOCYTES. 

 1 and 2, Mulberry shape; 3, prickly pear shape; 4, shadow. 



Changes in the size of the red corpuscles are frequently observed 

 in disease. Cells possessing a diameter of about 6ju are found in 

 anemia, while cells with a diameter of lO/x and over are encountered in 

 persons suffering from pernicious anemia, leukemia, chlorosis or cir- 

 rhosis of the liver. The former are known as microcytes and the latter 

 as megalocytes or macrocytes. When both their size and shape are 

 1 Archiv fiir mikr. Anat., i, 18. 



