TO 
Olive, Mitotic division of the niiclei of the Cyanophyceae. 
immersion objective, 2 mm, 1,30 IST. A., and Zeiss compensating ocular 12. 
Figs. 6, 7, 8, 10, 11, 14, 17, 26, 27 were made witli a compens. ocular 18, and 
tlie 2 mm objective. 
Tlie abreviations Mein, and Heid, stand for Flemming's triple stain 
and HeicLenhain’s iron haematoxylin, respectively. 
Plate I. 
(Figs. 1—6, Oscillatnria tenuis.) 
Fig. 1. A living filament, showing the blue green peripheral chroma- 
tophore and the colorless central portion. The cyanophycin granules and 
two slime globules are also shown. 
Fig. 2. A section stained witli Heid, and eosin. The filament was 
first dried on the ground before fixing. At the end of several montlis, 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 witli the He gl er S0 2 -Alcohol mix- 
ture, and stained witli Heid, and eosin. The central body Ts overstained 
and appears to be, in some cases, shrunken and poorly fixed. 
Fig. 4. A cross section of a well fixed filament, similar to that shown 
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 shrunken central body shows in cross section such an one 
as that represented in the uppermost cell in fig. 2. 
Fig. 6. A section stained witli 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 FroeJilichia.) 
Fig. 7. Stained with Flem. The mantle portion of the spindle is im- 
stained. Slime globules, also unstained, are shown, imbedded in one side 
of the nucleus. 
Fig. 8. A preparation stained with Heid, and eosin. Fach sectioned 
nucleus shows one slime globule, stained light bluish with the 1. c. aematoxylin. 
The minute chromosomes äre black and the achromatic spindle is very liglit 
bluish. The chroniatophore is reddish in color. 
Fig. 9. A longitudinal 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 purplisli chro¬ 
mosomes are more distinct in cells 1 and 4 that in 2 and 3. The central 
spindle is usually bluish, but is sometimes so densely fibrous that it may 
be even stained bright red with the safranin. The mantle fibers, leading 
from the chromosomes, are very 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 much overstained. 
The mantle fibers are shown, leading from the central body completety to 
tlie protoplasmic „Schicht“ along the partition wall. 
Fig. 13. A section overstained with Flem. No differentiation into 
cliromatin and achromatin can be seen. A secondary division may be ob¬ 
served in the two contiguous 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. 
