THE GENUS MICROCOCCUS 225 



culture method, and still erroneously included in the genus 

 by later observers. Such are M. prodigiosus, M. chlorinus, 

 M. cyaneus, and M. violaceus of Cohn (1872), M, phos- 

 phoreus, Cohn, and M. fuscus } Eisenberg. Short bacilli 

 corresponding to all these forms are now well known, while 

 no cocci have been isolated in recent years which form red, 

 green, blue, or brown pigments, or which produce phos- 

 phorescence (except the peculiar chromogenic streptococcus 

 that has been discussed in Chapter VII). It is most 

 probable that short rods were mistaken for cocci in the 

 original observations; or the macroscopic characters may 

 have been due to contaminating bacilli in a culture origi- 

 nally made up of cocci. 



