428 



Scientific Proceedings (132) 



2. Sodium and calcium chlorides, singly and in combination 

 in the concentrations used depress the buffer ratios, particularly 

 in the physiological zones of P H . 



3. The acidic P H values at which the buffering power of 

 Bact. coli becomes insignificant are approximately those at which 

 this organism is known to be spontaneously agglutinable and 

 to be isoelectric with the menstruum. 1 It is therefore signifi- 

 cant to note that a similar reduction in the buffer ratio is attained 

 at alkaline as w T ell as at acidic reactions. This observation sug- 

 gests the existence of a second, an alkaline isoelectric point for 

 bacteria. 



212 (2172) 



The influence of certain electrolytes upon the electrical charge 



of bacteria. 2 



By C.-E. A. WINSLOW, I. S. FALK and M. F. CAULFIELD. 



[From the Department of Public Health, Yale School of Medicine, 

 New Haven, Conn.] 



In connection with an extensive series of studies on the effect 

 of electrolytes upon the various properties of the bacterial cell, 

 we have measured the electrical charge of vegetative cells of 

 B. cereus (chosen on account of its large size) by the direct 

 microscopic method described by Northrop. 3 In conducting these 

 experiments a voltage of known magnitude (112 v.) is applied 

 to non-polarizing zinc-zinc sulphate electrodes and the direction 

 and velocity of migration of the bacteria in unbuffered suspen- 

 sions determined by observing through the microscope the 

 time taken by the bacterial cells to cross a definite space on the 



1 Michaelis, I)cut. wed. Wochensch, 1911, xxxvii, 969; Eiscnberg, Centr. 

 Bait., 1919, lxxxiii, 70, 472, 561; Northrop and DeKruif, J. Gen. Physiol, 

 1922, iv, 639. 



2 Studios here reported were aided by a grant from the Loomis Research 

 Fund of the Yale School of Medicine. 



8 J. Gen. Physiol, 1922, iv, 629. 



