38 MORPHOLOGY OF THE BACTERIA. 



These globules of sulphur have been observed 

 in Monas Okenii, Bacterium sulphuratum, Ophi- 

 domonas, and the different species of Beggiatoa, 

 both in fresh water, in putrid sea-water, and in 

 thermal sulphur waters. It will be seen when we 

 speak of the physiology of these organisms what 

 their role is in the elimination of sulphur and the 

 formation of sulphuretted hydrogen. 



We have said, in speaking of the colored bac- 

 teria, that some borrow their color from the sur- 

 rounding medium, and that others, on the contrary, 

 have a color of their own. The protoplasm of the 

 latter contains a granular coloring matter, which 

 is ordinarily yellow, blue, or red. The red color- 

 ing matter is most common, and this has been best 

 studied, and appears to be the best known. 



One of . these colors which gives a pink tint 

 (peach color) to Bacterium rubescens, Ray-Lank. 

 ( Clathrocystis roseopersicina, Cohn) ; 3Ionas vinosa, 

 Ehrb., M. Okenii, Cohn; M. gracilis, Warming; 

 Rhabdomonas rosea, Cohn; M. Warmingii, Cohn; 

 Ophidomonas sanguinea, Ehrb. ; Merismopedia 

 littoralis, Rabenh. ; etc., has been studied by Ray- 

 Lankaster, who has given to it the name of bac- 

 terio-purpurine. It is insoluble in water, soluble 

 in alcohol, ether, carbolic acid, glycerine, and 

 fatty oils, — characteristics which make it resemble 

 chlorophyll. It has also a characteristic spectrum. 



Other red coloring matters which appear to be 

 different have been found in Monas prodigiosa, 

 Ehrb.; Bacillus ruber, Cohn; and Micrococcus ful- 

 vus, Cohn. These should not be confounded with 



