Olive. Mitotic divisiou of tlie'nuclei of tlie Cyanopliyceae. 41 



Fig. 10. A cross seci ion oi O. Froehlichia, staiued with Flem., in which 

 the clark piii-plitili clironiatiii granules and dinüy detiiied achrrimatiii appear 

 to lie in a nnclear vacuole. ISncli an appearance, in wliick a niiclear niem- 

 brane appears to be visible, occurs but rarely in vegetative cells. 



Fig. 17. From tlie sanie preparation as fig. 14. Tlie chromatin and 

 acliromatin appear to be fused tngetlier. The lowennost nnclens iirobably 

 represents a section of a spirenie condition, in wliicli the hssion plane has 

 l)egTin to divide the disc shaped figure. 



Fig. 18. Cross section of 0. princeps, stained with Heid. The chromosomes 

 number abont 32. The cnarse meshwork of kiuoplasm represents the mantle 

 tiber region; in the niiddle is a denser portion corresponding to the narrow 

 part of the constricted central spindle in fig. 10, cells 1 and 4. The chro- 

 niatophore is also distinctly kinoplasnn"c. 



Fig. 19. A section of 0. FroehlicJiia, after treatment for tlu-ee days 

 with pepsin. The cyanoplu^cin graniiles and portions of the protoplasm 

 have evidently been digested. The indigestible chi'omatin granules are 

 stained dark blne with Heid., wh^le the cytoplasmic portion which reniains 

 nndigested is nnstained. The slime globtiles may be seen in other sections 

 to be still nndigested. 



Fig. 20. A cross section of the sanie, stained with Heid. and eosin. 

 In the shninken protoplast may be seen clu'omatophore, chromatin, and 

 achi'omatin. 



Fig. 21. A section of a species of Oscillatoria, stained with anilin blue 

 and eosin. The cyanophycin grannies along the partition walls are stained 

 red; the centi'al body a dim blue, sometimes with darker, denser, or gi-ann- 

 lar portions showing; the peripheral clrromatophore is dark blne. 



Fig. 22. 0. splemJens, similarly stained, showing the large, sometimes 

 ii'regular, cyanophycin grannies. 



Fig. 23. A cross section of the same species as in. fig. 21, similarly 

 stained, with cyanophycin grauxües red, Ij'ing in a dimly blue, protoplasniic 

 netn'ork. 



Fig. 24. A cross section of 0. FrocJdicJiia, stained with Flem. About 32 

 bright reddish chromosomes may be connted. The peripheral clu-omatophore 

 is stained somewhat bluish. 



Fig. 25. A section from the same preparation as that showri in 

 tig. 24. in Avhich the chi-omatin and acliromatin appear to be somewhat 

 fused together. 



Fig. 20. Cross section of Oscillatoria sp., stained with Heid., showing 

 about 19 chromatin granules; some possibly belong to the lower gronp of 

 cliromosqmes. This and the next fig-nre probably represent spireme stages. 



Fig. 27. A similar preparation, showing a large, dark-colored slime 

 globule, imbedded in one side of the nnclens. Here only 13 chromosomes 

 (•an be seen. 



Fig. 28. An end view of a cell from a filament of O. Froehlichia, which 

 was left three days in cliloroform water, in order to extract the ph^^cocyanin. 

 The bright green coior of the chromatophore appears to be iTniformly dif- 

 fused, and no indications of plastids are seen. The granules in the central 

 portion are probably cyanophycin and chromatin. 



Fig. 29. A side view of a portion of a lilament of the same species, 

 similarly treated. The cells are still enclosed within their walls. Tlie peri- 

 pheral jiortion is colored a niucli darker green than the middle. The dis- 

 tinct granulatioii appears only in the middle and is obviouslj' caused by the 

 same granules seen in end view in fig. 28. 



Fig. ;50. A freshly treated filament of 0. Froehlichia, lying in a 20"',) 

 Solution of KNO3. Compare the plasmolized cells here with the digested 

 lilament in fig. 31. 



Fig. 31. A filament of Oscillatoria digested for several days in pepsin, 

 at abont 35" Cent.; then stained with Heid. The granules are dark hlue, 

 and they lie in a Light bluish central liody. The outer pc/tion of the proto- 

 plasm is nnstained. 



(Figs. 32—34, Phormidium sp., aU stained with Heid.) 



Fig. 32. 16 chromosomes show very distinctly in this cross section. 



