THEORY OF EVOLUTION 185 



several nuclei and in addition there is scattered 

 material or particles called chromidia that are 



\cx_ 

 . 



FIG. 91. Difflugia corona. (After Cash.) 



supposed to be chromatic in nature and related 

 to the material of the nuclei, possibly by direct 

 interchange. 



When Difflugia divides, part of the proto- 

 plasm protrudes from the opening and a new 

 shell is secreted about this mass which becomes 

 a daughter individual. The behavior of the 

 nucleus and of the chromidia at this time is ob- 

 scure, but there is some evidence that their 

 materials may be irregularly distributed be- 



