48 PATHOGENIC BACTERIA. 



Meunier 1 found that when the influenza bacillus of 

 Pfeiffer is inoculated upon blood agar in conjunction with 

 the Staphylococcus aureus its growth is greatly favored. 

 This does not depend upon any fertilizing effect of the 

 staphylococci, but upon a change which they bring about 

 in the hemoglobin, by which it is better adapted to the 

 requirements of the influenza bacilli. 



A similar advantageous association is pointed out by 

 Sauarelli, who found that the Bacillus icteroides grows 

 well and retains its vitality long when grown in company 

 with certain of the moulds. 



Rarely, the presence of one species of microorganism 

 entirely eradicates another species. Hankin found that 

 the Micrococcus Ghadialli destroyed the typhoid and colon 

 bacilli, and suggested the use of this coccus to purify 

 waters polluted with typhoid. 2 



(i) Temperature. — The question of temperature is of 

 importance from its bearing upon sterilization. Accord- 

 ing to Frankel, bacteria will scarcely grow at all below 

 i6° and above 40 C. 



The researches of Fliigge show that the Bacillus sub- 

 tilis will grow very slowly at 6° C, and as the tempera- 

 ture is elevated it is said that until 12.5 C. is reached 

 fission does not occur oftener than every four or five 

 hours. When 25 C. is reached the fission occurs every 

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

 hour. 



A few forms of bacteria which can grow at very high 

 temperatures (6o°-70° C.) are described as thermophilic. 

 They are found in manure piles and in hot springs. 

 Tsiklinsky 3 has described two varieties of actinomyces 

 and a mould cultivated from earth that grow well at 

 48°-68° C, and not at all at the temperature of the 

 room. 



1 Societe de Biologie, Stance du n Juin, 1898; La Semaine midicale, June 

 15, 1898. 



2 Brit. Med. Jour., Aug. 14, 1897, p. 418. 



3 A'uss. Archiv.f. Path., etc., Bd. v., June, 1898. 



