MORPHOLOGY AND TAXOXOMY OF MASTIGOPHORA 2S1 



Family 4. Chlamydomonadidse, Biitschli.— These are small, soli- 

 tary flagellates, with from 2 to 4 Hagella, 1 green chromato- 

 phore, red stigma and with 1 to several pyrenoids or with none 

 at all. Reproduction occurs by longitudinal or transverse division 

 in either resting or motile phases (Fig. 134j. If in the resting stage 

 large gelatinous aggregates (Palmella-phase) result. Such aggre- 

 gates of Chlamydomonas niiaUs (HcBmatococcvs niialis) under con- 





Fig. 135. — Types of colonial flagellates. A, Stephanosphara pluvialis, after Kiihn; 

 B, Spondylomorum quarternarium from Doflein after Stein; C, Pleodorina calif ornica 

 from Doflei;i after Chatton. 



ditions of lack of nitrogen and phosphorus in the environment give 

 rise to the phenomenon of "red snow" or "blood snow" in northern 

 or alpine regions. Fertilization occurs by the permanent imion of 

 iso- or anisogaraetes. 



Famili) 5. Volvocidse, Ehrenberg.— The organisms included in 

 this family rejjresent the highest t^-pe of development of the plant- 

 flagellates. They are colonial and the constituent cells are fre- 

 quently differentiated for different functions. Individuallv the 



