Generic Characters in the Coccaceae 173 



violet for one and one-half minutes; Gram's solution, one and one- 

 half minutes; 95 per cent alcohol, three minutes. Counterstained 

 with Bismarck brown for one-half minute. Reaction recorded 

 as — (decolorized in both tests); ±: (stained once and decolorized once); 

 or + (stained in both tests). 



4. Vigor oj surface growth on agar streak after 14 days at 20°. — 

 Recorded as i (very faint); 2 (meager); 3 (good); 4 (abundant); 

 or 5 (very heavy). 



5. Amount of acid produced in 2 per cent dextrose broth after 



N 

 14 days at 20°. — Determined by titration against — NaCl in the cold 



with phenolphthalein as an indicator. Recorded value is the difference 

 between inoculated tubes and sterile controls, expressed in cubic 

 centimeters to nearest loth. 



6 . Amount of acid produced in 2 per cent lactose broth. — Same 

 conditions as under 5. 



7. Formation of nitrites in nitrate solution. — Recorded value 

 is the number of tubes giving positive test for nitrites out of a series 

 of 10, grown for seven days at 20°. 



8. Formation of free ammonia in nitrate solution. — Same method 

 as under 7. 



9. Comparative growth after 14 days^ growth on agar streak at 

 20° and 57°, respectively. — Recorded as i (much more vigorous 

 at 20°); 2 (more vigorous at 20°); 3 (equal); 4 (more vigorous at 

 37°); or 5 (much more vigorous at 37°). 



10. Chromo genesis. — Hue and chroma of pigment produced on 

 agar at 20° after 14 days, determined by comparison with color 

 scheme as described later. 



11. Depth in cm. of gelatin liquefaction in tube of i mm. diame- 

 ter after 14 days at 20°. 



It would be well to extend this series of tests by a study of the 

 cell-grouping in broth, motiUty, fission on the agar block, fermenta- 

 tion of saccharose, effect of acid and alkaUne media, and the ther- 

 mal death-point. 



I. Habitat. 



The distribution of the cultures isolated among the various habi- 

 tats was as follows: (i) diseased conditions, 59; (2) normal body, 



