Olive. Mitotic division of tlie nuclei of tlie (Vanophyeeae. 
■n 
it lies; in some cases, liowever, e. g., Cylinclrospermum and Ana- 
baena, tlie poles of tlie figure are niore nearly pointed tlian in 
otliers. In nearly all instances, tlie pressure of tlie multitude of 
cvanopliycin granul es wbicb lie in tlie surrounding cytoplasm, 
as well as tlie presence of slime globules, wbicb are usually 
deeplv inibedded in one side of tlie central body, determine 
largely certain peculiarities and irregularities of its sliape. (pp. 
18, 19, 20. 22.) 
In Gloeocapsa , owing to tlie peculiar metbod of Separation 
of tlie two daugliter spiremes. tlie acbroniatic figure remains 
tlirougliout tlie anapliases so inconspicuous (see figs. 70 and 71. 
e. g.), tliat tlie terrn spindle would hardly be applied in tiiis 
case. Between tlie two spiremes of üg. 71, liowever, tliere is 
present an acbromatic portion wliicli corresponds obviously in 
position to tbe central spindle, wliile tlie pulling übers (if any. 
indeed, be necessar; ly present), must now be located in an 
entirely new position, at tbe ends of tbe cell, so as to effect 
tbe peculiar Separation wliicli follows. (p. 29.) 
(2) Spireme. We bave, furtlier, a spireme tbread, partic- 
ularly evident in tbe cells of Gloeocapsa , in wliicli separate and 
distinct cbromatin granules are usually demonstrable. Sucb a 
spireme is most appropriately called a „segmented spireme", 
and tbe cbromatin granules inibedded in it, since tbeir nimiber 
is constant for tbe species, and since tliere is no furtlier indi- 
cation of transverse üssion, correspond to tbe cbromosomes. 
Sbould tbis be true, tben we liave tbe unprecedented pbenomenon 
of a cbromosome made up of a single cbromatin granule, or 
cbromomere. (pp. 22, 29.) 
In tbe opinion of tbe writer, tbe dividing central body in 
ügs. 8 and 10. seen in section, so tliat tbe long axis agrees in 
position witb tbe long axis of tlie nucleus in Gloeocapsa (ügs. 
74, 75), corresponds to a certain extent to tbe undoubted spireme 
in tbe latter ügures. Tbus we sbould bave, in Gloeocapsa , a 
simple, more or less spiral spireme, placed crosswise to tbe sub- 
sequent plane of division of tbe cell, and in Oscillaioria and 
tlie otlier forms, a convoluted spireme placed parallel to tbe 
subsequent plane of division. It is biglily probable, furtbermore, 
tliat Oscülatoria and otlier ülamentous forms also bave tbeir 
cbromatin granules arranged, like tliose of Gloeocapsa , in tbe 
form of a segmented spireme. If tbis be true, tben tbe cases 
of apparent fusion of cbromatic and acbromatic elements, seen 
particularly in preparations stained witb Flemming’s triple 
stain (as in ügs. 7, 10, 17, 25), are misleading, and tbe granules 
sbould all appear instead as sliarply deüned as is sliown in 
üg. 8. Tbe acbromatin, . liowever, undoubtedly varies consider- 
ablv in density during tlie nuclear clianges. Düring tbe times 
of greatest density, tbe acbromatic portion sometimes stains as 
deeply as cbromatin, so tbat an appearance of tbe fusion of tbe 
two into a more or less solid tbread may be given. Tbis opinion 
is supported by tbe fact tbat it can be readily demonstrated by 
