MaBCH 6, 1903.] 



SCIENCE. 



377 



the conclusion from the following experi- 

 ments. 



A variety which produces pyocyanin 

 only on a medium consisting of asparagin 

 1 per cent., MgSO, 0.02 per cent., K^HPO^ 

 0.1 per cent., can be made, by gradually in- 

 creasing the phosphate to 0.5 per cent., to 

 produce both pyocyanin and fluorescent 

 pigment. In this case there is very little 

 pyocyanin and a great deal of the fluores- 

 cent pigment. Another variety, which was 

 producing both pyocyanin and the fluores- 

 cent pigment, was made to produce the 

 fluorescent pigment alone on asparagin 0.2 

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

 0.5 per cent. This same variety upon as- 

 paragin 1 per cent., MgSO^ 0.05 per cent., 

 KoHPOj 0.2 per cent., strongly acid, pro- 

 duced pyocyanin alone. 



Turning now to the common B. fluores- 

 cens liquefaciens, which on asparagin 1 per 

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

 per cent., produced the fluorescent pigment. 

 I gradually lessened the phosphate and in 

 another series the sulphate to determine 

 whether or not this bacillus could be in- 

 duced to take up the pyocyanin function. 

 The fluorescent pigment disappeared and 

 the growth became colorless, but no 

 pyocyanin was produced. 



The conclusions to be drawn are that the 

 same variety of B. pyocyaneus can be made 

 to produce pyocyanin alone, pyocyanin and 

 a fluorescent pigment, or the fluorescent 

 pigment alone, according to the medium 

 upon which the bacillus is grown ; but that 

 the purely fluorescent bacilli can not be 

 made to take up the pyocyanin function. 



A Preliminary Chemical Study of Various 

 Tubercle Bacilli: E. A. de Schweinitz 

 and M. Dorset, Biochemic Laboratory, 

 Washington, D. C. 



Dr. de Schweinitz gave, for himself and 

 Dr. Dorset, a brief resume of the work 

 carried on by the Biochemic Laboratory 



of the Department of Agriculture so far, 

 upon a chemical examination of the fol- 

 lowing bacilli: bovine, horse, swine, avian, 

 virulent hiunan and attenuated human. 

 He pointed out that the conclusions which 

 might be drawn from these analyses indi- 

 cate a closer resemblance in the composi- 

 tion of the germs between the moderately 

 virulent human bacilli and the bovine and 

 swine, than between the moderately virulent 

 hiunan and the very attenuated human 

 bacilli. The analyses also indicate a closer 

 relationship in composition between the 

 attenuated human bacilli and the avian 

 bacilli, than between the two varieties of 

 human bacilli used. He also called atten- 

 tion to the fact that a similar comparative 

 examination of hiunan bacilli and bovine 

 bacilli of various degrees of virulence was 

 being carried out. Attention was called, 

 further, to the fact that the large amount 

 of phosphoric acid obtained from the germs 

 indicated that this constituent was abso- 

 lutely necessary for the proper develop- 

 ment of these bacilli, and it was noted that 

 for a number of years in all the work in 

 the study of tubercle bacilli in the Bio- 

 chemic Laboratory, culture media had been 

 prepared with the addition of acid potas- 

 sium phosphate, and that sodium chloride 

 had been entirely eliminated. The results 

 had been uniformly more satisfactory than 

 with any liquid medium that has been used 

 for the tuberculosis bacilli. The impor- 

 tance of a chemical study, not only of the 

 tubercle bacilli themselves, but also of their 

 products, was emphasized. 



The authors further presented the his- 

 tory of a case of generalized tuberculosis 

 in a child of five years of age that had 

 been brought up on milk. The cultures 

 obtained from the mesenteric glands of this 

 child had produced generalized tubercu- 

 losis in a heifer, after subcutaneous inocu- 

 lation, within about a month. Drawings 

 which showed the appearance of the lung 



