Conditions Prejudicial to Growth of Bacteria 63 



7. Alternating currents of a 3-inch Ruhmkorff coil passed through 

 bouillon cultures for ten hours favor growth and pigment production. 



8. High-frequency, high potential currents Tesla currents have 

 neither antiseptic nor bactericidal properties when passed around a bac- 

 terial suspension within a solenoid. When exposed to the brush dis- 

 charges, 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 distance 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. 



1 1 . Tubercular sputum exposed to the Rontgen rays for six hours, 

 at a distance of 20 mm. from the tube, caused acute miliary tubercu- 

 losis of all the guinea-pigs inoculated with it. 



12. Rontgen rays have no direct bactericidal properties. The clin- 

 ical results must be explained by other factors, possibly the production 

 of ozone, hypochlorous acid, extensive necrosis of the deeper layers of 

 the skin, and phagocytosis. 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. 



Movement. Rest seems to be the condition best adapted 

 for micro-organismal development. Slow-flowing movements 

 do not have much inhibitory action, but violent agitation, 

 as by shaking a culture in a machine, may hinder or prevent 

 it. This explains why rapidly flowing streams, whose cur- 

 rents are interrupted by falls and rapids, should, other 

 things being equal, furnish a better drinking-water than a 

 deep, still-flowing river. 



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

 not inhibit the growth of the anthrax, typhoid or colon 

 bacilli or the pneumococcus, but sometimes facilitates it. 



Association. Symbiosis is the vital association of different 

 species of micro-organisms by which mutual benefit to one 

 or the other is brought about. Antibiosis is an association 

 detrimental to one of the associated organisms. Bacterial 

 growth is greatly modified by the association of different 

 species. Coley found the streptococcus more active when 

 combined with Bacillus prodigiosus; Pawlowski, that mixed 

 cultures of Bacillus anthracis and Bacillus prodigiosus were 

 less virulent than pure cultures of anthrax; Meunier, that 



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



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



t " Centralbl. f. Bakt.," etc., I Orig. 4, xxxvn, Sept. 23, 1904, 

 p. 151. 



Societe de Biologic, Seance du n Juin, 1898, "La Semaine medi- 

 cale," June 15, 1898. 



