vin BINARY FISSION 87 



long axis, like Haematococcus (p. 25), and this double move- 

 ment produces the appearance of undulation. 



Most Bacteria are colourless, but three species (Bacterium 

 viride, B. chlorinum, and Bacillus wrens) contain chlorophyll, 

 and several others form pigments of varying tints and often 

 of great intensity. For instance, there are red, yellow, 

 brown, blue, and violet species of Micrococcus which grow 



FIG. 1 6. Bacillus subtilis, showing various stages between single 

 forms and long filaments (Leptothrix}. 



on slices of boiled potato, hard-boiled egg, &c., forming 

 brilliantly coloured patches; and the yellow colour often 

 assumed by milk after it has been allowed to stand for a 

 considerable time is due to the presence of Bacterium 

 xanthinum. 



All Bacteria multiply by simple transverse fission, the 

 process taking place sometimes during the motile, sometimes 

 during the resting condition. Frequently the daughter-ceils 

 do not separate completely from one another but remain 



