CHAPTER VII. 



MICROCOCCUS (Hallier, Cohn). 



BY the specific term micrococcus is understood a minute 

 spherical or slightly oval organism (spherobacterium, Cohn), 

 that like other bacteria divides by fission (schizomycetes), and 

 that does not possess any special organ, cilium or flagellum, by 

 using which it would be capable of moving freely about. 

 Micrococci, like other granules when suspended in a fluid 

 medium, show (Brownian) molecular movement. Micrococci 

 propagate always by simple division, never by any other 

 means, e.g. gemmation and spores. All assertions to the 

 contrary are based on incorrect observations. All micrococci 

 possess a delicate membrane of cellulose, and owing to this 

 resist the action of alkalies and acids. The contents are 

 homogeneous and highly refractive while active, pale when 

 inactive. They consist like those of other bacteria of myco- 

 protein (Nencki). The size of micrococci varies within con- 

 siderable limits, say 0*0008 0'002 millimetres, or even a little 

 more. Micrococci vary greatly as regards both size and mode 

 of growth. All multiply by slightly elongating and then divid- 

 ing by a transverse constriction into two : a dumb-bell ; each 

 of these again divides into two, either transversely or in the 

 same direction as before. The new elements of successive 

 divisions may remain connected, and thus form a chain (or 

 mycothrix, Itzigsohn and Hallier ; torulaform string, Cohn), 

 or they separate into single organisms or dumb-bells. In some 

 ppecies there is a pre-eminent tendency to form chiefly dumb- 

 bells, in others to form shorter or longer chains generally more 

 or less curved. 



Such exquisite chains one meets with sometimes in serum of 

 blood exposed to the air for some days, and in pleural and 



