10 Ol i Yc. ^ritotic ilivision of Ili<' miclt'i of tlie Cyauophyceae. 



inunersiou objective, 2 iiiiii. 1.30 N. A.. and Zeiss compensating ocular 12. 

 Fis:s. 0. 7, 8, 10. 11, 14, 17, 2»j, 27 were niade witli a compen.s. ociilar 18. and 

 the 2 mm objective. 



The abreviations Flem. and Heid. stand for Flemming's triple staiu 

 and TTcidenliai n"s inm haematoxylin, respectively. 



IMalc I. 



(Figs. 1 — tj. Oscillutoriu Icnuis.) 



Fig. 1. A living filament, showing the bliie green jieripheral chronui- 

 tophore and the colorless central portion. Tlie cyanophycin granules and 

 t\v(i slime globales are also shown. 



Fig. 2. A section stained with Heid. and eosin. The filament was 

 tirst dried on the groiiud before fixing. At the end of soveral months. the 

 dried material was still living. The central body is overstained and, in some 

 cells. appears to have long chromosomes ; in certain cells, the central body 

 seems to be undergoing direct division. The shrunken cytoplasm is 

 stained red. 



Fig. 3. From a preparation fixed with the Hegler S02-Alcohol mix- 

 ture, and stained with Heid. and eosin. The centi'al body is overstained 

 and appears to be, in sonie cases, shrunken and poorly fixed. 



Fig. 4. A cross section of a well fixed filament. similai- to that showu 

 in fig. 6. The dark chromatin granules are surrounded by bluish kinoplasm. 



Fig. 5. A cross section of a filament treated similarly to that shown 

 in fig. 2. The slirunken central body shows in cross section such an oue 

 its Ihat represented in the uppermost cell in fig. 2. 



Fig. 6. A section stained with Heid. The minute black chromatin 

 granules lie in a bluish achromatin. The lowermost cell appears to be in a 

 spireme condition. 



(Fig. 7 — 9, Oscillatoria Froehlichia.) 



Fig. 7. Stained with Flem. The mantle portion of the spindle is \\\\- 

 stained. Slime giobules, also unstained, are shown, imbedded in one side 

 of the nucleus. 



Fig. 8. A preparation stained with Heid. and eosin. Fach sectioned 

 nucleus shows oue slime giobule, stained light bluish "witli the 1. c. aematoxyliu. 

 The minute chromosomes are black and the achromatic spindle is xery light 

 bluish. The chromatophore is reddish in color. 



Fig. 9. A longitudiual section, stained with Heid., showing at a. bc 

 and at d, three division centers in which. division of the central body is at 

 its maximum. 



(Figs. 10 — 13, Oscillatoria princeps.) 



Fig. 10. A thin section stained with Flem. The dark ^^nrplisli chro- 

 mosomes are more distinct in cells 1 and 4 that in 2 and 3. The central 

 spindle is tisually bluisli, b\it is sometimes so denselj^ fi])rous that it may 

 be even stained bright red with the safranin. The mantle fibers, leading 

 from the chromosomes, are veiy dimly stained. Cyanophycin and slime are 

 unstained. 



Fig. 11. A section stained with methylene blue and eosin; the central 

 body appears almost homogeneous. A secondary division may also be 

 observed. 



Fig. 12. A preparation which was stained four times unsuccessfully 

 in Flem., then in Heid. and eosin. The central body is nuicli overstained. 

 The mantle fibers are shown, leading from the central body completely to 

 the protoplasmic „Schicht" along the partition wall. 



Fig. 13. A section overstained with Flem. No differentiation into 

 chromatin and achi-omatin can be seen. A secondary division may be ob- 

 served in the two contigiious daughter central bodies. 



Fig. 14. Section of an undetermined species of Oscillatoria, stained 

 with Flem. The' nuclei in the four cells at the right of the figure appear 

 to be in a resting condition. 



Fig. 15. A cross section of a small species of Oscillatoria, stained with 

 Flem. in which about 12 — 16 bright red chromatin granules may be counted. 



