26 



CHLOROPHYCEAE 



compactly in the centre and are frequently flattened from mutual 

 pressure, are connected to each other by protoplasmic threads that 

 are withdrawn during reproduction. Each colony is enclosed in a 

 gelatinous matrix with an outer watery sheath, and, together with 

 the next two genera, exhibits some degree of polarity in its pro- 

 gression. When reproducing asexually the cells first lose their 

 flagellae and then each one gives rise by several divisions to a 

 daughter colony. In sexual reproduction signs of anisogamy are to 

 be found, and the zygote germinates giving one to three biflagellate 

 spores which then develop into new colonies. 



*Chlamydomonadaceae :£'M(fonw« {eu, well ; dorina, meaningless !). 

 Fig. 17. 



The colonies are spherical or ellipsoid, the posterior end often 

 being marked by mamillate projections. They contain sixteen, 



Fig. 17. Eudorina elegans. A, vegetative colony. B, transverse section showing 

 structure and protoplasmic connections, a = outer layer, b = inner layer of muci- 

 lage. C, formation of daughter coenobia. D, E. illinoiensis, showing somatic 

 cells, V. (After Fritsch.) 



thirty-two (commonly) or sixty-four biflagellate cells, which are not 

 closely packed and are frequently arranged in transverse rows, the 

 flagellae of the individual cells emerging through funnel-shaped 

 apertures. In most species all the cells give rise to daughter colonies, 

 but in E. illinoiensis and E. indica the four anterior cells are much 

 smaller and cannot produce gametes or daughter colonies. This 



