ALG^ 



79 



tween the cells. Parthenogenesis is probably a not in- 

 frequent phenomenon, and marks the extreme point of 

 divergence from the typical green algse. 



Both Phseophycese and Rhodophycese reach a far 

 higher degree of specialization of the plant body than 

 is ever met with among the Chlorophycese, but there 

 is no evidence that either group has given rise to any 

 higher types of plant structure than exist at present 

 within the classes themselves, the most specialized of 

 the existing forms representing probably the highest 

 expression of these peculiar structural types. 



The assumed relationships of the main group of Algse 

 may be illustrated by the following diagram : — 



Dinoflageliata 

 Brown Algce 



VolvooineiB 

 Green Algee 



SiphonesB 



