Olive, Mitotic division of tlie nuclei of tlie Cyaiiopliyceae. 
19 
down (figs. 82 and 83). In Gloeocapsa polydermatica Kützing 
(figs. 62, 64, 76), and Kostoc commune Vauclier, eight chromo- 
somes could nsuaily be counted. In Oscillatoria tenuis Agardli 
fig. 4), Oscillatoria sp. (figs. 15, 26, 27), Phormidium. sp. (figs. 32, 
33), Calofhrix thermalis Hansgirg 1 ) (fig. 43), tliere are sixteen 
cliromosomes. 
Tlie cells in Oscillatoria Froelichia Kützing and 0. prin- 
ceps V auch er are so sbort tbat tlie central body takes on tlie 
form of a flattened disc, appearing in section as sbown in tbe 
figs. 7 —13. Tlie shallowness of tbe nucleus undonbtedly accounts 
for tbe difficulty in determining definit ely tbe nurnber of tbe 
ebromosomes, since tliose wliicli belong to tbe lower group niay 
easily be counted witli tliose in tbe upper focus. Tliere are, 
liowever, in all probability, tliirty two in tbe cells of fliese two 
species, altbougli for a long time I tbongbt tliere were abont 
twice tbat number (figs. 18, 24). 
In tliose cells in wbicb tbere are sixteen cliromosomes, one 
maj usually connt in median longitudinal view tbree or fonr 
(figs. 2, 6, 14, 17, 34, 37); wbile in tbe two large Oscillatorias , 
we may frequently see as rnany as eiglit in side view (figs. 7, 
10). Tliis fact leads one to tlie conclusion tbat Tolypothrix also 
bas sixteen ebromosomes, since botli Kolli and AYager sliow 
in tbeir drawings ab out fonr or live in median section; tbis 
opinion is, liowever, at variance witli tbat of Kolli, wlio liolds 
tbat tbe cells in Tolypothrix contain but fonr to six. 
It will be noticed, in most of tlie drawings of longitudinal 
sections of tbe various filamentous forms (figs. 8—13, 17, 34, 37) 
tbat tliere is sbown, in some cases mueb rnore clearly tlian in 
otliers, minute fibrillär projections from tbe central body. Tliese 
are seen in one drawing only (fig. 12) to run from tbe central 
body completely to tbe cross walls. In certain instances in 
wbicb tbe bleacliing of tlie stain bas been carried a step too 
far, tliese fibrils are not at all visible (figs. 6, 7). In fig. 12, 
tbe combination of iron liaematoxylin witli eosin and tbe failure 
to wasb tbe stains out sufficiently bave resulted in a black, un- 
differentiated central portion, and a reddisli cytoplasm. The 
fibrillär projections, in tliis instance, and tbe tbin, delicate cyto- 
plasmic layer lining tbe cross walls, as well as tbe peripheral 
cbromatopliore, are all stained red witli tlie eosin. AYe can now 
observe tliat tlie projections are connected at tlieir outer ex- 
tremities witli tbe lining layer of protoplasm along tbe cross 
partition walls, and further, tbat at tbe central body end, eacli 
is joined witli a chromosome (figs. 8, 10, 17, 34, 37). In tlie 
spaces between tlie fibers, as will be explained later, are granules 
of reserve food, tbe cyanophycin granules (see fig. 21). Tbere 
remains no doubt in tbe mind of tlie writer tliat tliese fibrillär 
projections represent tbe mantle fibers, or „Zugfäsern“ of tbe 
mitotic figure. Tliey are attacbed to tlie wall at tlie one end 
0 Kindly detennined by Prof. 0. Kirebner. 
9^ 
