SCHIZOPHYTA SCHIZOPHYCEAE 



185 



Fig. 31. Schizophyta. Schizophyceae. Blue Green Algae. 1. Chrococcits turgidus 

 x 400. 2. Gloeocapsa sanguinea x 400. 3. Nostoc vcrrucosum. 3a. A pair of chains. 

 4. Cliamaesiphon confervicola x 400; at the right, a caenobium; at the left, germinating 

 arthrospores. 5. Rirularia minutula x 200. 6. Anabaena macrosperma x 100; at the right, 

 a caenobium; at the left, germinating arthrospores. 7. Plectonema Tomasinianum x 200. 



8. Filaments of Tolypothrix aegagropila; c central body, ch chromatin bodies, x 100. 



9. Lyngbya aestuarii x 150; at the right filiaments with hormogonia (ho). In all figures, 

 sp spores, h heterocyst. Fig. 1, 2, 3, after Cooke; Fig. 4, 5, 7, after Hausgirg; Fig. 8, 

 after Nadson; Fig. 3a, 6, 9, after Wettstein. 



North America, especially common in ponds and the plankton of lakes. Other 

 species are C. roseo-persicina and C. Kiitsingiana, the former being especially 

 common in ponds and ditches which contain a great deal of decaying vegetable 

 matter. The latter species is now generally referred to the genus Coleosphacr- 

 ium, and the C. aeruginosa to the genus Microcystis. 



OSCILLATORIACEAE 



Cells in filaments, apical cells disc-shaped with sheaths variable, sometimes 

 wanting, heterocysts absent; form hormogonia. Common representatives, Oscilla- 

 toria and Lyngbya which at times are common in fresh water. 



Oscillatoria, Vauch 



The plant consists of more than one cell forming a simple filament held 

 together by a common but stout gelatinous sheath, the cells being packed to- 



