OONPBRVOID ALG2E. 267 



absent, or have not yet been observed ; when present, 

 they will be found projecting on one or both sides of 



Fig. U5. Conferva:. 



I, Volvox globator. 2, A section of volvox, showing the flagellate margin of 

 the cell. 3, A portion more highly magnified, to show the young volvo- 

 eina, with their nuclei and thread-like attachments. 4, Spirogyra, near 

 which are spores in different stages of development. 5, Conferva flocossa. 

 6, Stigeoclonium protensum, jointed filaments and single zoospores. . 7, 

 Staurocarpus grnnlis, conjugating filaments and spores. 



the filament, being somewhat longer than the latter. 

 Filaments inclosed in sheaths never, or but slightly, ex- 

 hibit their peculiar motion, although they may be seen 

 sliding in them, backwards and forwards, or leaving 

 them altogether. 



The filaments themselves have been supposed to con- 

 sist wholly of protoplasm ; this view, however, is scarcely 

 correct, since the protoplasm is enclosed in a cell- mem- 

 brane. The cellulose always shows cross-markings 

 corresponding to the strise when such are observable 



