88 MORPHOLOGY OF THE BACTERIA. 
These globules of sulphur have been observed 
in Monas Okenu, 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 réle 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); Monas vinosa, 
Ehrb., JZ. Okenii, Cohn; I. 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 
