| Table Notes: | |(D)| (E) | +-------------------------+-----------------------------------+---+-----------+ Table Notes: (A) * Liquefies gelatine. (B) + = motile. - = non-motile. (C) + = acid or gas production. ± = slight acid production. O = no change. (D) + = indol production. ± = slight indol production. - = no indol formed. (E) + = acid production. - = alkali production. O = no change in reaction. C = clot. 21. Determine the pathogenicity for mice (subcutaneous inoculation) and rabbits (intravenous inoculation) of the streptococci isolated. On the facing insert page is reproduced a blank from the author's Laboratory Water Analysis Book, by means of which an exact record can be kept, with a minimum of labour, of every sample examined. B. ~Concentration Method.~ The remaining organisms referred to on page 426 are more conveniently sought for by the concentration method. _Collection of the Sample._--The quantity of water required for this method of examination is about 2000 c.c., and the vessel usually chosen for its reception is an ordinary blue glass Winchester quart bottle, sterilised in the hot-air oven, and over this a paper or parchment cap fastened with string. The bottle may be packed in a wooden box or in an ordinary wicker case. The method of collecting the sample is identical with that described under the heading of Quantitative Examination; there is, however, not the same imperative necessity to pack the sample in ice for transmission to the laboratory. _Apparatus required_: Sterile Chamberland or Doulton "white" porcelain open mouth filter candle, fitted with rubber washer. Rubber cork to fit mouth of the filter candle, perforated with one hole. Kitasato serum flask, 2500 c.c. capacity. Geryk air pump or water force pump. Wulff's bottle, fitted as wash-bottle, and containing sulphuric acid (to act as a safety valve between filter and pump). Pressure tubing, clamps, pinch-cock. Retort stand, with ring and clamp. Rubber cork for the neck of Winchester quart, perforated with two holes and fitted with one 6 cm. length of straight glass tubing, and one V-shaped piece of glass tubing, one arm 32 cm. in length, the other 52 cm., the shorter arm being plugged with cotton-wool. The rubber stopper must be sterilised by boiling and the glass tubing by hot air, before use. Flask containing 250 c.c. sterile broth. Test-tube brush to fit the lumen of the candle, enclosed in a sterile test-tube (and previously sterilised by dry heat or by boiling). Case of sterile pipettes, 10 c.c. in tenths. Case of sterile pipettes, 1 c.c. in tenths. Case of sterile pipettes, 1 c.c. in hundredths. Tubes of various nutrient media (according to requirements). Twelve Buchner's tubes with rubber stoppers. Pyrogallic acid tablets.