44 Biology of Bacteria 



different species of bacteria 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 

 when the influenza bacillus of Pfeiffer is inoculated upon 

 blood agar together with Staphylococcus aureus its growth 

 is favored by a change which the staphylococci bring about 

 in the hemoglobin. 



A similar advantageous association has been pointed out 

 by Sanarelli, who found that Bacillus icteroides grows best 

 and retains its vitality longest when grown in company with 

 certain of the molds. 



Rarely, the presence of one species of micro-organism 

 entirely eradicates another. Hankin found that Micro- 

 coccus ghadialli destroyed the typhoid and colon bacilli, 

 and suggested the use of this coccus to purify waters pol- 

 luted with typhoid. f 



An interesting experimental study of the bacterial an- 

 tagonisms with special reference to the Bacillus typhosus, 

 that the student should read, is by W. D. Frost, and appears 

 in the "Journal of Infectious Diseases," 1904, i, p. 599. 



(e) Extremes of Temperature. According to Frankel, 

 bacteria will rarely grow below 16 and above 40 C., but 

 Fliigge has shown that Bacillus subtilis will grow very 

 slowly at 6 C. ; at 12.5 C. fission does not take place 

 oftener than every four or five hours; at 25 C. fission occurs 

 every three-quarters of an hour, and at 30 C. about every 

 half hour. 



A few forms of bacteria grow at very high temperatures 

 (6o-7o C.) and are described as thermophilic. They are 

 found in manure piles and in hot springs. Tsiklinsky J 

 has described two varieties of actinomyces and a mold 

 that he cultivated from earth and found able to grow well 

 at 48-68 C., though not at all at the temperature of the 

 room. 



* Societe de Biologic, Seance du 11 Juin, 1898; "La Semaine medi- 

 cale," June 15, 1898. 



t "Brit. Med. Jour.," Aug. 14, 1897, p. 418. 



j "Russ. Archiv f. Path.," etc., Bd. v, June, 1898. 



