80 MICKO-ORGANISJIS FROM THE BRISBANE AIR. 



times the diplococci divide transversely, forming tetrads. This, 

 with a sHght variabihty in the size of the individual cocci, 

 exhausts the morphology of these simple organisms. After 

 careful and repeated examinations, I was unable to find any 

 ground of distinction from microscopical appearance in the 

 eight varieties. None of them exhibited any independent 

 motility, though Brownian movements were, of course, very 

 marked. The distinctions between them depend entirely on 

 their mode of growth on various media. In describing them it 

 will be convenient to denote the varieties by letters of the Greek 

 alphabet, as it would not be justifiable lo give them distinct 

 names until they have been compared with cocci previously 

 described. In two, Coccus y and Coccus /x, the growths are pink ; 

 in Coccus {■, vivid orange ; in Coccus ?/ and Coccus A, bright 

 yellow; in Coccus 6 and Coccus v, whitish ; in Coccus ^, brownish. 

 Another point of distinction is the presence or absence of the 

 power of liquefying gelatine. Two, coccus ( and coccus A, 

 never liquefy the gelatine, however old the growth may be. 

 On the other hand, coccus 6 liquefies the gelatine rapidly ; 

 coccus -)], coccus V, and coccus ^ slowly ; coccus y and coccus /*, 

 after growing for a long period without any sign of 

 liquefaction, slowly give rise to this after the lapse of several 

 weeks. The slow occurrence of liquefaction is best deter- 

 mined by streak cultures on the surface of gelatine which 

 has set in an obliquely inclined tube. The first sign of 

 liquefaction is the formation of a groove in the surface of the 

 gelatine occupied by the growth ; at a later period the growth 

 slides down to the bottom of the tube. By noting the date on 

 which the groove is first distinct, the comparative rapidity of 

 liquefaction can be estimated. For mstance, in one experiment, 

 during which the temperature ranged between 16 deg. C. and 

 22 deg. C, coccus and coccus v formed a groove on the second 

 day, coccus y on the fifth day, coccus ^ on the nineteenth day, 

 coccus y on the twenty-fourth day, coccus /x on tho forty-eighth 

 day. 



Growths of these cocci on potato show no peculiarity 

 except in their coloration and rapidity of growth. Growths in 

 liquid broth show no peculiarity of any kind— merely a turbidity 

 with a fine deposit formed by the organisms. Coccus 9 is an 

 exception. Broth cultures and liquefied gelatine cultures of 



