Mabch 6, 1903.] 



SCIENCE. 



375 



logical characters of human and bovine 

 tubercle bacilli when grown on egg have 

 been left for future report. 



Studies on Quantitative Variations in Gas 

 Production in the Fermentation Ttihe: 

 C.-B. A. WiNSLOW, Massachusetts Insti- 

 tute of Technology, Boston, Mass. 

 Experiments were made to determine tlie 

 amoimt of variation in gas formation in a 

 series of dextrose broth tubes filled with 

 the same batch of culture medium and in- 

 oculated with the same organism. For 

 inoculation, measured portions of an aque- 

 ous suspension of the surface agar growth 

 of a strain of B. coli were used. A wide 

 variation between individual tubes was ob- 

 served. Thus in one case with tubes re- 

 ceiving the same amount of culture ma- 

 terial the amount of gas varied from 20 per 

 cent, to 62 per cent, of the closed arm after 

 16 hours, and from 38 per cent, to 86 per 

 cent, after 64 houi-s. This was not simply 

 a variation in the rapidity of the evolu- 

 tion of gas; for in this instance the maxi- 

 mum of gas fonned in a given tube at any 

 time varied from 42 per cent, to 86 per 

 cent. By averaging the results obtained 

 in a number of tubes more general rela- 

 tions became apparent. During the first 

 12 hours the amount of gas formed de- 

 pended upon the amount of material used 

 for inoculation, and the relative proportion 

 of hydrogen was greater than at a later 

 period. Between 24 and 48 houi"s the 

 maximum of gas was generally formed 

 with the classical gas formula of two to 

 one, and after 48 hours a marked decrease 

 of total gas occurred, due to the absorp- 

 tion of carbon dioxide. The principal 

 point brought out was the wide variation in 

 individual tubes due to some unknown fac- 

 tor, and apparently only to be avoided by 

 making a series of duplicate analyses. 



Preliminary Note on Chromogenic Cultures 

 of B. diphtkerice: Hibbert Winslow 

 Hill, Boston Board of Health Labora- 

 tory. 



Six stock cultures of B. dlphtherice, the 

 originals of which had been isolated be- 

 tween March, 1901, and January, 1902, 

 and since kept on serum, with reinoculation 

 at intervals of one to two months, showed 

 gradually increasing yellow color when 

 streaked on serum. 



Recently (December, 1902) this colora- 

 tion became so striking as to attract def- 

 inite attention. One of the six cultures 

 (4014) isolated October 18, 1901, from a 

 clinical case of diphtheria, and then typ- 

 ical morphologically and typically virulent 

 to guinea-pigs, was selected for examina- 

 tion. The morphology and virulence, re- 

 tested in December, 1902, were still typical. 

 Cultures from this stock developed the 

 color on serum at 37° C, slightly in one 

 day; by the third day the color was very- 

 marked— a clear bright yellow. The 

 growth, removed by scraping, is treated 

 with chloroform, which dissolves the pig- 

 ment. After filtration to remove the 

 bacilli, evaporation to dryness deposits the 

 pigment, which is then found soluble in 

 chloroform and in ether, but not in water. 

 The same culture grown on agar for the 

 same time yields only an ordinary dirty- 

 white tint. When treated similarly, such 

 dirty-white cultures yield a small amount 

 of faint grayish-brown pigment. From 

 fresh uninoculated serum of the same lot 

 ether extracts a yellow pigment, but chloro- 

 form does not. 



The writer has observed cultures of B. 

 diphthericB showing a faint pink color, and 

 others which, especially when old, show 

 quite dark-brown or black coloration. 



The Chemistry of Bacterial Pigments: M. 

 X. Sullivan, Brown University. 

 While gro\\'ing bacteria upon synthetic 



