910 ON THE EXAMINATION OF WATER FROM THE SYDNEY SUPPLY, 



name of Spirobacteria (Spirillum, Spirochaete). Then again, 

 exclusively anaerobic bacteria, such as the bacillus of butyric acid 

 fermentation, and the bacillus of malignant oedema, will not, at 

 least under ordinary circumstances, develop in nutrient gelatine. 



These groups, however, it must be admitted, form only a small 

 part of the whole class of bacteria ; yet it would be very important, 

 at any rate, to have in the gelatine-plate process a means for their 

 detection. By far the greater majority of bacteria, as already 

 mentioned, grow readily in or on the common nutrient gelatine, 

 Koch's comma-bacillus of cholera asiatica, and the bacillus of 

 typhoid fever (Eberth) can, if present in the water under examina- 

 tion, scarcely escape notice. (*) 



(2.) It is not always justifiable to regard the number of bacterial 

 colonies met with on the plates of gelatine as corresponding exactly 

 to as many individual germs in the sample of water under considera- 

 tion. Bacteria, as is well known, have a tendency to form 

 various kinds of aggregations, or to combine in groups of growth 

 which are not always so easily separable into their individual 

 components. Therefore, as von Malapert-Neufville proposes (f ) 

 the best way to say is : — 



One cubic-centimeter of the water used 



in the experiment a, yielded A bacterial colonies. 



55 55 fr) 55 ■** 55 55 



and so on. 



A few other objections to Koch's method of water-test are but 

 of a slight and immaterial character ; they can be satisfactorily met 

 by paying the strictest care and attention to the prescribed course 

 and manner of manipulation. 



Before examining the water which, as already stated above, was 

 derived from a tap in the Linnean Hall, and once only from one in 



(*) Conf. also Robert Freiherr von Malapert-Neufville, " Bacteriolog. 

 Untersuchung d. wichtigsten Quellen d. stadtischen Wasserleitung Wiesba- 



dens und einer Anzahl Mineral-Quellen " Zeitschrift f. 



Analytische Chemie von Fresenius, Jahrg. 25, Heft. 1, Wiesbaden 1886, 

 pp. 39-88. 



(t) Loc. cit. 



