Conditions Prejudicial to Growth of Bacteria 43 



passed through bouillon cultures for ten hours favor growth 

 and pigment production. 



8. High frequency, high potential currents Tesla cur- 

 rents have neither antiseptic nor bactericidal properties 

 when passed around a bacterial suspension within a solenoid. 

 When exposed to the brush discharges, ozone is produced 

 and kills the bacteria. 



9. Bouillon and hydrocele- fluid cultures in test-tubes of 

 non-resistant forms of bacteria could not be killed by 

 Rontgen rays after forty-eight hours' exposure at a dis- 

 tance of 20 mm. from the tube. 



10. Suspensions of bacteria in agar plates and exposed 

 for four hours to the rays, according to Rieder's plan, were 

 not killed. 



11. Tubercular sputum exposed to the Rontgen rays for 

 six hours, at a distance of 20 mm. from the tube, caused 

 acute miliary tuberculosis of all the guinea-pigs inoculated 

 with it. 



12. Rontgen rays have no direct bactericidal properties. 

 The clinical results must be explained by other factors, 

 possibly the production of ozone, hypochlorous acid, ex- 

 tensive necrosis of the deeper layers of the skin, and phago- 

 cytosis. The action of the x-rays upon bacteria has been 

 investigated by Bonome and Gros,* Pott,f and others. 

 When the cultures are exposed to their action for prolonged 

 periods, their vitality and virulence seem to be slightly 

 diminished. They are not killed by the x-rays. 



(c) Movement. Rest seems to be the condition best 

 adapted for micro-organismal development. Slow-flowing 

 movements do not have much inhibitory action upon the 

 growth of bacteria, but violent agitation, as by shaking a 

 culture in a machine, may hinder or prevent it. This ex- 

 plains why rapidly flowing streams, whose currents are 

 interrupted by falls and rapids, should, other things being 

 equal, furnish a better drinking-water than a deep, still- 

 flowing river. 



Galli-Valerio J has shown, however, that agitation does 

 not inhibit the growth of the anthrax, typhoid or colon 

 bacilli or the pneumococcus, but sometimes facilitates it. 



(d) Association. Symbiosis is the vital association of 



* "Giornal. med. del Regis Esercito," an 45, u. 6. 



t "Lancet," vol. n, No. 21, 1897, 



i "Centralbl. f. Bakt./' etc., I Orig. 4, xxxvii, Sept. 23, 1904, p. 151. 



