CHAPTER VIII. 



THE EFFECT OF LIGHT, ELECTRICITY, PRESSURE, 

 AGITATION, DRYING, AND ASSOCIATION WITH OTHER 

 MICRO-ORGANISMS UPON BACTERIA. 



VERY little is known about the influence of electricity 

 on bacteria. The majority of the observations hereto- 

 fore made on this subject would seem to indicate that 

 there is no direct action of the galvanic current on 

 bacteria; but the effect of heat and the electrolytic in- 

 fluence on the culture liquid may produce changes which 

 finally sterilize it. Gottstein and Spilker have recently 

 made experiments with an induction current from a 

 dynamo machine. They passed the current through 

 a spiral wire, which was wrapped around a test-tube 

 of glass containing the micro-organisms to be tested, 

 suspended in water. The bacillus prodigiosus, sus- 

 pended in sterilized distilled water and contained in 

 test-tubes having a capacity of 250 c.c., was subjected 

 to a current of 2.5 amperes -{- 1.25 volts for twenty- 

 four hours. The temperature did not go above 30 C. 

 No growth occurred when the organism tested was sub- 

 sequently planted in nutrient gelatin. It was found that 

 stronger currents were effective in a shorter time, but 

 in no case was sterilization effected in less than an hour. 

 These experiments, however, have not been confirmed. 



Meltzer has shown that while slight agitation of 

 cultures of bacteria acts favorably on their develop- 



