440 BACTERIAL FLORA OF THE SYDNEY WATER SUPPLY, 



motile a further observation was made upon a young bouillon 

 culture. 



The difficulties of diagnosing bacteria in the absence of typical 

 cultures is admitted, and in the descriptions which follow the 

 points which led to the identification of the organisms are noted. 

 Cultural characters which have not been previously published, 

 are also given. One of the points in which I have found a 

 difference is the size and especially the breadth of the organism. 

 Bacteria differ in dimensions slightly, according to the medium 

 in which they are grown. The sizes which I have given are of 

 the bacteria when cultivated upon agar, and they have been 

 measured by a method which I shall describe in a future paper. 

 In describing the colours or shades of colour, I have used as a 

 reference the tints upon a sample card of enamel paints issued 

 by the firm of Blundell, Spence and Co., London. 



With a temperature of 15° C, I have found an average of 

 about 100 bacteria in the laboratory tap-water during the months 

 of May and June. The organisms are not at all evenly distri- 

 buted in the water as it issues from the tap. For example, in 

 five plates inoculated with 0-1 c.c. there developed upon Abba's 

 gelatine 15, 15, 12, 5 and 4 colonies; this is equal to an average 

 of 100 bacteria per cubic centimetre. 



Micrococcus candidus, Cohn. 



The organism measures from - 5 to 0*6 /x in diameter, and 

 occurs singly, in twos and in groups. It stains deeply with 

 methylene-blue. On agar, there is formed a broadening, translucent 

 white, raised, moist glistening stroke. The iridescent and white 

 surface colonies, on agar plate, are seen, under a sixty-fold magni- 

 fication, to be finely granular, and to have a clear, lacerate 

 margin. In gelatine stab culture the growth is filiform, with a 

 flat, spreading, white nail-head. 



Sarcina lutea, Schroter. 



This organism forms a narrow, moist glistening, convex, 

 canary-coloured ridge in agar stroke culture. The individuals 



