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 sulphui* 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); Monas tnnosa, 

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

 Rhabdomonas rosea, Cohn; M. Warmingii, Cohn; 

 Ophldomonas 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 9 

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

 vus, Cohn. These should not be confounded with 



