COCCOGONALES 



II 



disintegration, each portion growing into a new colony. The shape 

 of the colony is primarily determined by the environmental 

 conditions, and it can be changed by altering the environment 

 artificially. M. aeruginosa is a very common water bloom alga. 



*Chroococcaceae : Chroococciis (chroo, colour ; coccus, berry). Fig. 3 . 



The cells are single or else united into spherical or flattened 

 colonies each containing a small number of cells, the individual 





mi 



B 



\\Vi A 



Fig. 3. Chroococcus. A, C. turgidus, plant ( x 600). B, C. turgidus, protoplasmic 

 reticulum with accumulations of metachromatin at nodal points. /)^ = plasmatic 

 granules, mf = microsomes. C, C. macrococcus, normal daughter cell formation. 

 D, C macrococcus, daughter cell formation with retention of the parent envelopes. 

 (A, after Smith; B, after Acton; C, D, after Crow.) 



sheaths being homogeneous or, more frequently, lamellated. 

 Plants grown in water produce a concentric envelope but when 

 grown on damp soil the sheath is often asymmetrical. The outer 

 integument is not very gelatinous and indeed is quite thin in some 

 species. The colonies are either free-floating or else they form a 

 layer on the soil. A study of the cytology of this genus has shown 

 that C. turgidus represents the simplest condition with the meta- 



