28 NOTES ON MICRO-ORGANISMS. 
filtering material can be put in at any time (see Fig. 1). | Several 
modifications of this arrangement might be devised. Boiling is, 
Fic. 1, 
of course, the most effectual way of rendering a water innocuous, 
but the time consumed in the operation and subsequently cooling 
are drawbacks, not to mention the vapid taste of the liquid so 
treated. 
Water treated by Heisch’s method with sugar and kept ina 
warm place developes Bacteria in proportion to the combined 
phosphorus in solution. With a trace of phosphoric acid a free 
growth of Bacteria will at first take place, but they pass quickly 
into the Zoogleea state. Very good examples of Zoogleea can 
be obtained in this way. It may be mentioned here that phos- 
phorus in some form is just as necessary to the Bacterial life as to 
other living creatures and organisms. 
In connection with the growth and culture of organisms some 
important questions present themselves, viz. : — 
1. In what plasma or food stuff does the Bacterium thrive best ? 
Through what stages of development does it go? 
As to the products of decomposition by specific Bacteria ? 
How does the ferment behave in relation to oxygen ? 
How is it affected by temperature ? 
. As to the action of antiseptics ? 
An bY Pp 
Having obtained the specific Bacterium one is desirous. of 
