382 PROTOPLASM 



Findings by Falk indicate a possible relationship between the 

 virulence of bacteria and their electric charge. 



There are four known types of pneumococci, each of which 

 causes a distinct kind of lobar pneumonia. The types are num- 

 bered 1 to 4. From cultures of known pneumococcus types, Falk 

 took samples and measured their respective cataphoretic rates. 

 He found that type 3 moved the fastest when in a cataphoretic 

 chamber under the influence of an electric field; type 1 was next; 

 then type 2; and type 4 was the slowest. White mice were given 

 intraperitoneal injections of one of the four types of bacteria, 

 and the time of their death after injection noted. It was found 

 that the sequence of decreasing virulence for mice of the four 

 types of pneumococci was the same as that of the potential of the 

 bacteria, viz., 3, 1, 2, 4; in other words, the higher their electric 

 charge the more deadly the bacteria. Whether this result was a 

 matter of chance or there actually is such a striking relationship 

 between the virulence and the interfacial potential of bacteria 

 cannot be said. Further evidence obtained by Falk shows that 

 the mortality rate among 720 cases of human beings suffering 

 from lobar pneimionia decreases from 44.3 to 13.2 per cent with 

 the type of pneumonia in the order 3, 1, 2, 4, which is that of 

 decreasing potential. There are many kinds of bacteria, some of 

 which are deadly, some mildly toxic, some harmless, and some 

 useful, yet all possess electric mobilities which are, in magnitude, 

 not far removed from those of pneumococci. While the virulence 

 of one species of pathogenic bacteria is possibly directly propor- 

 tional to the cataphoretic potential, the mere possession of such 

 a potential does not necessarily make a bacterium toxic. What 

 it probably does, if at all effective, is to make the bacterium more 

 active; and if the bacterium happens to be a pathogen, then its 

 greater activity, due to charge, makes it more deadly. 



R. L. Thompson finds the same order of decreasing mobility of 

 pneumococci (3, 1, 2) as does Falk, but he is unable to correlate 

 this with the virulence of the bacteria. 



The Migration of Leucocytes. — It has long been known that 

 white blood cells (leucocytes) play an important part in wound 

 healing. They are always to be found in great numbers in the 

 vicinity of a wound. Their function appears to be primarily that 

 of scavengers; they ingest bacteria present at the seat of the 

 wound. They may also be agents in the production of wound- 



