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 of 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 1 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, motility, fission on the agar block, fermenta- 

 tion of saccharose, effect of acid and alkaline 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, 



