MICROCOCCUS TETRAGENUS CONCENTRICUS 257 



round islets appear, which when inoculation has been exten- 

 sive coalesce with one another, and by confluence of several 



Concentrically stratified 

 superficial growth 



Deep portion of the needle-track 



Concentric stratification in 

 sure in the gelatine 



FIG. 92. THRUST-CULTURE IN GELATINE OF MICROCOCCUS 

 TETRAGENUS COXCEXTRICUS. 



a larger roundish compound colony is formed, resembling a 

 holoblastic ovum in process of segmentation. Thrust-cul- 



