142 



Chlor&phyceae 



Bialosuknia ('09) has carefully studied the Pleurococcaceous Alga in the thallus of 

 LECANORA TARTAREA and named it Diplosphsera Ckodati, hut it might he hetter regarded 

 only as a form of a Protococcus modified by its long association with a fungus. 



Some of the Green Algae have become symbiotically related to various 

 animals. In the Protococcales ' zoochlorellse ' (of the genus Ghlorella) occur in 

 the cells of Hydra viridis and various Infusoria; a species of Carter ia is 

 intimately bound up with the nutrition and habits of the worm Convoluta 

 Roscoffensis: a member of the Ulotrichales (probably a Gongrosira} is 



c 



Fig. 94. The sponge Halichondria associated with the Alga Strucen. In 1 the Struvea is seen 

 emerging from the sponge at b; 2, & section through the sponge (schir) showing its canals (c) 

 and the branches of the Alga (a) traversing it in all directions ; 3, some isolated branches of 

 the Stmvea. 



apparently symbiotically associated with the common freshwater sponge, and 

 the siphonocladiaceous genus Struvea is similarly related to the sponge 

 Halichondria (fig. 94). 



Quite a number of the Chlorophycese are inhabitants of the Arctic and 

 Antarctic areas, and are capable of withstanding prolonged freezing. Among 

 these are several species of Chlamydomonas, and another species of this genus 

 (Chi. nivalis) is the Red Snow plant. In this connection the observations of 

 Teodoresco ('09) on the zoogonidia (= vegetative cells) of Dunaliella are 

 interesting, as he showed that their movements only ceased when the tem- 

 perature of the salt water had been lowered to somewhere between -- 17C. 

 and - 22-5 C. 



