COLEOCH.ETE 



191 



(Fig. 183), and CJicetophora,, are more 

 complex than Ulothrix, for they consist 

 of branching filaments of peculiar forms. 

 However, the cell structure, life his- 

 tories, methods of reproduction, and low 

 sexual conditions (isogamy) of these 

 types all show relationships to the Ulo- 

 tliricacea:. They are of especial interest 

 as leading up from the level of Ulo- 

 tlirix to the highest form of the Con- 

 fervales, the genus Cohoclicete. 



222. Coleochaete. Coleochcetc (family 

 Coleocli&tacece) contains a number of 

 species which live in fresh water, at- 

 tached to the stems and leaves of water 







weeds, and they frequently appear on 

 the sides of aquaria. Some of the forms 

 .are circular flat plates or cushions of 

 cells that really consist of systems of 

 filaments radiating out from a center. FlG - 18 ^- Cladophora 



Large, two-ciliate zoospores are formed Tmslai 'g e > much-branched, fil- 

 amentous alga, A, has many 

 singly in the cells. The female organ, species common in both fresh 



oogonium, is a large, flask-shaped cell and salt f wate ^ Zo< ' s P 01 -es, 



'/>, are formed generally 

 with a long neck (Fig. 185 A, 0). Its in terminal sporangia, and 



protoplasm forms a single spherical egg there are f ametes w ^ cl ;, fu . se 



in pairs, C, as in Ulothrix. 

 which nearly fills the lower Swollen The older cells contain large 



portion of the oogonium, and the neck 

 finally opens above to allow the en- 

 trance of the sperms. The male organs, 

 antheridia (Fig. 185, A, a), are small Confervales&ndSiphonales 

 cells, generally in groups, each of which develops a two-ciliate 

 sperm. 



and Draparnaldia are common on stones in clear brooks and in springs. 

 Cladophora (Fig. 184) is also a good type for laboratory study and very 

 common. 



numbers of nuclei, and this 

 form, with certain relatives 

 (family Cladophoraceee), oc- 

 cupy a position somewhat 

 intermediate between the 



