680 FLOCCULATION OF BACTERIA BY PROTEINS 



2. The zone of flocculation of protein- treated bacteria bears a 

 significant relationship to the isoelectric point of the protein used. 

 With the higher concentration of protein, agglutination occurs at or 

 near the isoelectric point of that protein; at reactions acid to this, 

 the bacteria carry a positive charge and are not agglutinated. With 

 diminishing concentration of protein, the zone of flocculation shifts 

 toward and goes beyond that characteristic of the untreated bacteria. 

 This occurs both in the presence and absence of salts. 



3. A diversity of other suspensions, such as sols of gold, mastic, 

 cellulose nitrate, cellulose acetate, Fe(0H)3, oil emulsions, and 

 erythrocytes, have been found by ourselves and others to exhibit a 

 similar altered stability when treated with proteins in the same way. 



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Coulter, C. B., /. Gen. Physiol, 1921-22, iv, 403. 



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Hoppe-Seyler, F., Handbuch der physiologisch — und pathologisch — chemischen 



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