THE AGGLUTININS 225 



occurs when the blood is shed may be one of shape. Thus 

 Weidenreich and others hold that red corpuscles are normally 

 bell-shaped, and that the moment they leave the vessels they 

 become biconcave discs. If there is an increase in the tension 

 generated at their surface of contact with the serum, the con- 

 ditions for rouleaux formation would appear to be present. 

 Weidenreich's facts have been strongly disputed, and are not 

 generally accepted. 



Rouleaux formation cannot be induced in corpuscles which 

 have been heated to 44 C. 



