38 



added B. ruber balticus only to the list of color producers. A 

 second set of flasks was inoculated from five day potato cultures, 

 with the result that B. prod. I III developed a slight trace of 

 pigment. Growth was most luxuriant for all the cultures in this 

 solution, but on the other hand B. ruber indicus I lost its power 

 of producing color by the concentration of the medium. 



Standard asparagin solution with the addition of 2,0 / glycerine 

 allowed luxuriant growth, but of the whole series B. plymouthensisl 

 only showed a slight trace of pigment. 



It seems evident from these experiments that the conclusions 

 drawn by Kuntze and Noesske regarding the necessity of MgS0 4 

 for pigment formation, and of phosphorus for growth, in the case of 

 B. prodigiosus, do not hold for all of the various strains going 

 under this name. Out of eight strains three did not form pigment 

 even under these conditions, although all were cultures in the height 

 of vigor; one culture produced pigment in the absence of one, and 

 two strains of a closely related form in the absence of both the 

 above substances. 



The more luxuriant development of some of the non-pigmented 

 cultures in comparison with the slighter growth of other colored ones, 

 notably B. ruber indicus, seems to confirm the statement made 

 by Noesske and quoted previously in this paper. Further light 

 upon the subject of correlation of chromogenesis and growth, as well 

 as upon the effect of the presence of carbohydrate in the nutritive 

 medium, was obtained by the following experiments. 



Table VII. 



