376 



SCIENCE. 



[N. S. Vol. XVII. No. 427. 



media, I noticed that often chromogenic 

 varieties became colorless. Accordingly ex- 

 perimenting to determine what salts, bases 

 or acids in addition to the organogens, car- 

 bon, hydrogen, oxygen and nitrogen, are 

 necessary for pigment production, I found, 

 with Jordan, that for the formation of 

 fluorescent pigment, sulphates and phos- 

 phates are required. Extending the re- 

 search to other pigments, such as those pro- 

 duced by B. pyocyaneus, B. prodigiosus, B. 

 ruber haUicus, B. rosaceus metalloides, B. 

 janthinus and B. violaceus, I found that 

 the characteristic pigments were produced 

 whenever there were present, in addition to 

 suitable compounds of carbon, hydrogen, 

 oxygen and nitrogen, phosphates together 

 with sulphates, chlorides or nitrates, irre- 

 spective of the base. Suitable compounds 

 of C, H, 0, N, are asparagin, and the am- 

 monium salts of succinic, lactic and citric 

 acids. The solutions containing asparagin 

 were the best, so that upon a medium con- 

 sisting of asparagin 0.2 per cent., MgSO^ 

 0.02 per cent, K^HPO^ 0.1 per cent., 

 glycerin 2 per cent., the pigments were 

 quickly produced. Magnesium and potas- 

 sium may be replaced by other bases, as 

 sodium or ammonium. If the glycerin is 

 left out the asparagin must be increased to 

 1 per cent, to get good pigment formation. 

 Upon media consisting of (NH4)3P04 0.1 

 per cent., (HN4)2S04 0.1 per cent, and 

 glycerin 2 per cent., there occurred a good 

 production of pigment. 



Replacing the asparagin and glycerin by 

 ammonium salts of organic acids, 0.2 per 

 cent, to 0.5 per cent., I found that while the 

 Succinate, lactate and citrate gave pigment, 

 the tartrate, oxalate, urate and formate, 

 though allowing gi-owth, were unfavorable 

 to chromogenesis. 



By testing the chlorides and nitrates as 

 to pigment formation, it was found that 

 upon a solution consisting of asparagin 1 



per cent., KaHPO^t 0.02 per cent., NaCl or 

 KCl 0.2 to 0.5 per cent, or KNO3 0.02 per 

 cent, the pigment was formed, though less 

 abundantly than when MgS04 was present. 

 On the other hand the sulphides, bromides 

 and iodides were unfavorable to pigment 

 production. 



The conclusions to be drawn are that, in 

 addition to suitable compounds of C, H, 

 0, N, phosphates and sulphates are neces- 

 sary for the fluorescent pigment, while for 

 the pigments of B. pyocyaneus, B. prodi- 

 giosus, B. rosaceus metalloides, B. ruier 

 ialticus, B. janthinus and B. violaceus, the 

 sulphates may be replaced by the chlorides 

 or nitrates. 



The Pyocyanin and Fluorescent Functions 

 of Bacteria: M. X. Sullivan, Brown Uni- 

 versity. 



Since Gessard's discovery in 1882 of a 

 bacillus which produced a blue or blue- 

 green pigment soluble in chloroform, many 

 experiments have been carried on not only 

 as regards the morphological characters of 

 the bacillus to which Gessard gave the 

 name of B. pyocyaneus, but also as to the 

 nature of its pigments. In the study of 

 B. pyocyaneus, many varieties have been 

 isolated, so that at present we have kinds 

 which produce pyocyanin alone, others 

 which produce both pyocyanin and a green- 

 ish-yellow fluorescent pigment, insoluble in 

 chloroform, but soluble in alcohol and 

 ether, and further, some perhaps degener- 

 ate types, which produce a fluorescent pig- 

 ment only. Now the question is, what is 

 the relation between the different varieties 

 of this bacillus? Are the varieties char- 

 acterized by the ability to produce a dif- 

 ferent pigment or pigments, or can the 

 same race be compelled to form different 

 colored products according to the medium 

 on which it is grown? That the latter 

 view is the correct one would seem to be 



