Olive, Mitotic division of tlie nuclei of the Cyanopliyceae. 41 
Fig. 1(3. A cross section of 0. Froehlicliiä, stained with Flein., in wliich 
tlie dark purplisli cliromatin graniiles and dimly defined achromatin appear 
to lie in a nnclear vacnole. Sucli an appearance, in wliich a nuclear mem- 
brane appears to be visible, occnrs bnt rarely in vegetative cells. 
Fig. 17. From the same preparation as hg. 14. The cliromatin and 
achromatin appear to be fnsed together. The lowermost nuclens probably 
represents a section of a spireme condition, in wliich the fission plane has 
begim to divide the disc sliaped hgure. 
Fig. 18. Cross section of 0. princeps, stained with Heid. The chromosomes 
niimber about 32. The coarse meshwork of kinoplasm represents the mantle 
hber region; in the middle is a denser portion corresponding to the narrow 
part of the constricted central spindle in fig. 10, cells 1 and 4. The chro- 
matopliore is also distinctly kinoplasmic. 
Fig. 19. A section of 0. Froehlichi a, after treatment for three days 
with pepsin. The cyanophycin graniiles and portions of the protoplasm 
have evidently been digested. The indigestible cliromatin graniiles are 
stained dark blue with Heid., while the cytoplasmic portion wliich remains 
undigested is unstained. The slime globules may be seen in other sections 
to be still undigested. 
Fig. 20. A cross section of the same, stained with Heid, and eosin. 
In the shrunken protoplast may be seen cliromatophore, cliromatin, and 
achromatin. 
Fig. 21. A section of a species of Oscillatoria, stained with anilin blue 
and eosin. The cyanophycin granules along the partition walls are stained 
red; the central body a dim blue, sometimes with darker, denser, or granu- 
lar portions showing; the peripheral cliromatophore is dark blue. 
Fig. 22. 0. splendens, similarly stained, showing the large, sometimes 
irregulär,, cyanophycin granules. 
Fig. 23. A cross section of the same species as in fig. 21, similarly 
stained, with cyanophycin granules red, lying in a dinily blue, protoplasmic 
network. 
Fig. 24. A cross section of 0. Froehlicliiä, stained with Flem. About 32 
briglit reddisli chromosomes may be counted. The peripheral cliromatophore 
is stained somewhat bluish. 
Fig. 25. A section from the same preparation as that shown in 
hg. 24, in wliich the cliromatin and achromatin appear to be somewhat 
fused together. 
Fig. .26. .Cross section of Oscillatoria sp., stained with Heid., showing' 
about 19 cliromatin granules: some possibly belong to the lower group of 
.chromosomes. This and the next hgure probably represent spireme stages. 
Fig. 27. A similar preparation, showing a large, dark-colored shme 
globule, imbedded in one side of the nucleus. Tiere only 13 chromosomes 
can be seen. 
Fig. 28. An end view of a cell from a hlament of 0. Froehlicliiä , wliich 
was left three days in cliloroform water, in Order to extract the phycocyanin. 
The briglit green color of the cln'omatophore appears to be uniformly 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 filament of the same species, 
similarly treated. The cells are still enclosed within their walls. The peri¬ 
pheral portion is colored a much darker green than the middle. The dis- 
tinct granulation appears only in tlie middle and is obviously caused by the 
same granules seen in end view in fig. 28. 
Fig. 30. A freshly treated filament of 0. Froehlicliiä, lying in a 20° 0 
solution of KN0 3 . Compare the plasmolized cells liere witli the digested 
hlament in hg. 31. 
Fig. 31. A hlament of Oscillatoria digested for several days in pepsin, 
at about 35° Cent.; then stained with Heid. The granules are dark blue, 
and they lie in a light bluish central body. The outer portion of the proto- 
plasm is unstained. 
(Figs. 32—34, Phormidium sp., all stained with Heid.) 
Fig. 32. 16 chromosomes show very distinctly in this cross section. 
