12 
O live, Mitotic division of tlie nuclei of tlie Cyanopliyceae. 
of tlie conclusions liave already been given in December in a 
brief resume before tlie botanical section of the American 
Association for tlie advancement of Science. 
I take pleasure in acknowiedging my great obligations to 
tlie Carnegie Institution of Washington for a grant, by means 
of wkicli I liave been enabled to pursue tliese investigations in 
the laboratory of Professor Strasburger. To Professor Stras¬ 
burger particularly, for bis many kindnesses and for bis 
unfailing interest and belpful advice; and to bis assistant, 
Dr. Max Koernike, and to otbers in tlie Botanical Institute of 
the University of Bonn, I am also deeply indebted. 
Historical review. 
Among tlie tbirty or more who liave written on tbe cell 
structure of fliese organisms, it is impossible to find any two 
writers wlio agree in all details. Indeed, in seeking to disentangle 
tbe literature relating to tbis subject, one finds tliat several 
autbors even disagree witb tbeir own earlier views. It is, 
moreover, at times almost impossible to gain from tlie text an 
autbor’s exact meaning. For example, it is difficult in tbe 
extreme to make certain, wben Hieronymus used tbe expression 
„tbe cyanopbycin granules represent tbe nucleus of higher plants“, 
wbetber he really had in mind tbe cyanopbycin granules or tbe 
slime globules, or „red granules“ of Bütscbli. It is bigbly 
probable, bowever, tliat be meant tbe latter. And it is, moreover, 
not at all easy to follow understandingly Zukal’s researches, 
remarkable for tbeir opacity, and interpret wbetber bis many 
nuclei in tbe cells of tlie Cyanophyceae were slime globules or 
cyanopbycin granules; yet tliese two kinds of granulär inclusions 
are readily distinguislied from each otber in tbeir staining and 
Chemical reactions as well as in tbeir location in tbe cell. 
In several of tbe more recent articles on tbis group, notably 
in tliose of Fischer (97), Hegler (01), and Kohl (OB), are 
given excellent reviews of tbe literature relating to tbe subject. 
It bas been thought better, tlieref'ore, for tbe purposes of brevity, 
to present in tbis paper a fable (pp. 2,3), Condensed mostly from 
Hegler s admirable review, sbowing very concisely tbe more im¬ 
portant conclusions wliich liave been reached witb reference to 
tlie principal topics concerning tbe cell, viz., tbe cyanopbycin 
granules, tbe slime globules, tbe manner of distribution of blue 
and green coloring matters, and lastly, tbe nature of tliat portion 
witb wbicb tlie writer is in tbis paper more directly concerned, 
tbe so-called „central body“. In no otber way, it seems to.me, 
can tbe astounding confusion wbicb prevails be so graphically 
presented. Wliere great doubt exists as to tlie meaning of tbe 
author, I liave followed my Interpretation witb a question (?). 
Later, tlie views of several writers will be more fully discussed. 
Material aiul metkods. 
Tbe material for tbe present researcli was collected for tlie 
most part in green liouses, tlie large Oscillatoria princeps from 
