84 BOTANY 



filaments show active swaying and revolving movements, and when 

 in contact with a solid substratum, they creep about actively, soon 

 spreading themselves in a film with the free ends of the filaments 

 radiating from the centre of the mass (Fig. 56, A). The hormogonia 

 of Nostoc, and other forms which do not usually exhibit movement, 

 often show, for a time, active creeping movements by means of which 

 they escape from the gelatinous envelope and seek a new spot to 

 establish themselves. 



Classification of Schizophyceae (Kirchner, 8) 

 SCHIZOPHYCE.E (BLUE-GREEN 



Ord. I. Coccogonece. Single-celled. 



a. Reproduction by simple fission. Fam. 1. Chroococ- 



caceae. 



b. Reproduction by conidia. Fam. 2. Chamaesipho- 



nacese. 



Ord. II. Hormogonece. Multiplication by cell-rows (hormogonia) 



which often show creeping movements. Simple 



or branched filaments, often with sheath or gela- 



tinous envelope. 



a. Simple filaments of cylindrical cells, no resting-spores 



or heterocysts. Fam. 3. Oscillatoriaceae. 

 6. Cells usually rounded : heterocysts, and often arthro- 

 spores. Fam. 4. Nostocacese. 



c. Filaments enclosed in sheath, showing false branch- 



ing, usually showing base and apex ; heterocysts 

 and resting-spores usually present. Fam. 5. Scy- 

 touemataceae. 



d. Filaments enclosed in sheath, showing true branch- 



ing ; branches often attenuated ; heterocysts and 

 arthrospores. Fam. 6. Stigonemataceae. 



e. Filaments much attenuated with basal heterocyst; 



arthrospores sometimes present. Fam. 7. Rivula- 

 riacese. 



/ Filaments epiphytic, tapering at both ends ; no hete- 

 rocysts or arthrospores. Fam. 8. Camptotrichacese. 



PERIDINE^} (PERTDTNIALES) (SCHtJTT, 18) 



Among the important constituents of the surface life (Plankton) 

 of the ocean, and to a lesser degree of fresh water, are numerous uni- 

 cellular organisms whose affinities are not very clearly understood, 

 but which show evidences of their plant-nature. The most inipor- 



