EXPLANATIONS AND REFERENCES, 

 PLATE CLXXXVII. 



Figures magnified 250 diameters. 



PAGE. 

 Fig. 1-3. SCYTONEMA MiRABiLis, parts of three ti laments, . 255 



4. miurogomdia developed from the cells 



of the filaments, . . . 256 



5. the micrognnidia enlarging, forming 



cysts Microcystis forms, 



" 6. the Microcystis forms developing Gloeo- 



capsa forms, .... 256 

 ' 7-9. " " Nostoe forms from the last, . 



" 10-1-5. Nostoc filaments having developed 



sheaths, . . . 256 



Figs. 16, 17. imperfectly developed or faded filaments, 256 



Fig. 18-21. SCYTONEMA CORTEX, four samples of larger branching forms, 256 

 Figs. 22, 23. " two broken off ends, with cells singly, or 



in series sliding out, . . . 257 



Fig. 24. " two cells enlarging, developing macro- 



gonidia, .... 257 



Figs. 25, 26. these in turn increase in size, producing 



first, Microcystis forms, . . 257 



Fig. 27. " " then Nostoc forms, .... 2-\7 



Figs. 28. 29. " " from these cells are developed young plants, 257 



Fig. 30-33. young Nostoc forms producing Scytonema, 257,255 



" 34-37. " " young forms of Scytonema, . . 257 



