236 



PLANT STUDIES 



upon the return of favorable conditions. These may be 

 regarded as resting cells. So notable is the fact of repro- 

 duction by fission that Cyanophyceae are often separated 

 from the other groups of Algae and spoken of as " Fission 

 Algae," which put in technical form becomes Schizophyceae. 

 In this particular, and in several others mentioned above, 

 they resemble the " Fission Fungi " (Schizomycetes), com- 

 monly called "bacteria," so closely that they are often 

 associated with them in a common group called "Fis- 

 sion plants " (Schizophytes), distinct from the ordinary 

 Algae and Fungi. 



2. Chlorophtce^ {Green Algce). 



163. Pleurococcus. — This may be taken as a type of one- 

 celled Green Alga?. It is most commonly found in masses 

 covering damp tree-trunks, etc., and looking like a green 

 stain. These fine- 

 ly granular green 

 masses are found 

 to be made up 

 of multitudes of 

 spherical cells re- 

 sembling those of 

 Glceocapsa^ except 

 that there is no 

 blue with the chlo- 

 rophyll, and the 

 cells are not im- 

 bedded in such 

 jelly-like masses. 

 The cells may be 

 solitary, or may 

 cling together in 



colonies of various sizes (Fig. 204). Like Oloeocapsa^ a cell 

 divides and forms two new cells, the only reproduction 



Fig. 204. Pleurococcus, a one-celled green alga : A, show- 

 ing the adult form with its nucleus ; B, C, D, E, 

 various stages of division (fission) in producing new 

 cells ; F, colonies of cells which have remained in 

 contact.— C aldwell. 



