72 Peridiniese 



observed, coincides with observations on mutations in other organisms, and 



at. a. 



Fig. 52. Normal chain of Ceratium vidtur 

 Cleve, twisted at the fifth cell from the rear, 

 showing ventral view anteriorly, and dorsal 

 view posteriorly, x 100 (after Kofoid). 



Fig. 53. Mutating chain of Ceratium. The 

 posterior cell (JV) is C. tripos (0. F. M.) 

 Nitzsch, and cells I III are C. californiense 

 Kofoid. at.a., attachment area; ch.ch., 

 chain channel; fl.p., flagellar pore; v.a,, 

 ventral area covered by so-called 'ventral 

 plate.' x430 (modified from Kofoid). 



the instances of their occurrence suggest the influence of environmental 

 factors in producing the mutations. 



