Milotic division of the nuclei of the Cyanophyceae. 
By 
Edgar W. Olive. 
"Witli plates I—II. 
One of tlie most eagerly investigated as well as one of tlie 
most confusecl problems connected witli recent cytological re- 
searclies is that concerning tlie cell Organization of tlie Cyano- 
pliyceae. Is tliere a chromatophore; and if so, wliat is its natnre? 
Do es tlie cell possess a nucleus, or is it a non-nncleated organism? 
If tlie so-called „central body“ is a nucleus, tben is its division 
direct or indirect? Tliese constitute tlie niain disputed questions. 
Even after the exhaustive studies of Fischer (97), Hegler (01), 
Kohl (03), Wäger (03), and others, the real natnre of the 
central body has beeil regarded by the majority as still open 
to question. 
In attempting a comparison of the relations of the chromatin 
in the nuclei of niany of the lower plants, the writer found 
that thin sections of various Cyanophyceae showed witli corupar- 
ative clearness the internal structure of the cell, and also made 
quite evident the nuclear nature of the central body. Furthermore, 
tlie most modern methods of hxation and staining, as one would 
expect, have proved entirely successful, contrary to the statements 
of Hegler, who asserts tliat the tisual methods were not successful 
in procuring a sharp differentiation. In fact, it has beeil demon- 
strated to the writer*s complete satisfaction tliat the Hegler 
method of tixation itself gave, on the other hand, extremely poor 
results; and the conclusion has been reached, after mucli trial, 
that it is only by means of thin sections, properly stained, that 
certain important details of the cytology of these minute orga- 
nisms can be made out. 
The writer naturally hopes that in tlie present paper tliis 
difheult question has been brought somewhat nearer solution. 
As will be seen, however, the subject is regarded as far from 
closed, especially from a physiological point of view. Two 
papers have just appeared, the very exhaustive one by Professor 
Kohl and tlie long promised one by Mr. Wäger, and it has 
therefore been thought advisable to publish some of the results 
of this investigation at once, before it is fully completed. Some 
