PRODIGIOSIN PIGMENTS. 67 



several pigments, present great variation. (See Schneider, 

 A. K. I, 201, regarding spectra and peculiarities.) They 

 are, however, closely related to the widely distributed lipo- 

 chromes (pigment substances of fats, yolk of egg, etc. ) and 

 the carotin of yellow carrots. (Compare Leisenberg and 

 Zopf, C. B. XII, 659.) 



(6) Prodigiosin pigments. By prodigiosin I designate 

 the beautiful pigment of the Bact. prodigiosum and its 

 nearest relatives. It is soluble in ether as yellowish- 

 brown and in alcohol as garnet-red. It is turned yellow 

 by alkalis, violet-red by acids, and brownish-red by con- 

 centrated sulphuric acid. Zinc and hydrochloric acid re- 

 duce the pigment to a colorless leuko-product. The spec- 

 troscopic behavior is verj' characteristic. 



Violet pigments. In connection with the bacterium 

 violaceum, and also the Bacterium janthinum, there is pro- 

 duced, according to Schneider (verified by myself), a violet 

 pigment (janthin) which is insoluble in water, readily 

 soluble in alcohol, but insoluble in ether, benzol, and chloro- 

 form. If dry, it becomes yellow when treated with con- 

 centrated sulphuric acid and emerald-green when treated 

 with caustic potash. In alcoholic solution all strong acids 

 and ammonia produce a green or bluish-green color. With 

 zinc and sulphuric acid the color is destroyed (Schneider, 

 I. c). 



The beautiful blue pigment of the Bact. indigonaceum 

 Claessen was very incompletely examined by Claessen and 

 Schneider (l. c. ). This pigment is not dissolved by ordi- 

 nary solvents. Hydrochloric acid gives a transitory blue, 

 turning to a yellowish-brown solution. Also, other acids 

 in dissolving it cause its decomposition. Caustic potash 

 turns the color bluish-green. I am unable to add any- 

 thing further. 



Different from these is the blue pigment produced by 

 the Bacterium syncyaneum (blue milk), which I propose 

 to call syncyanin. It is also entirely independent of the 

 bacterio-fluorescein forms (see below). This pigment was 

 pointed out by Thumm as very unstable ; acids turn it 

 steel-blue, in weaker acids it is blue-black, neutral it is 

 black, alkaline it is brownish-black. For details see the 

 special part. 



