426 BOTANICAL GAZETTE [DECEMBER 
seems more probable that the first alternative will be found to be 
the explanation of these exceptional conditions in the red algae. 
DISCUSSION OF CYTOLOGICAL PHENOMENA. 
The nucleolus.—The morphology of the nucleolus and its behavior 
and function during mitoses have been studied in some detail for two 
decades by many investigators in both plant and animal cells. Vari- 
ous conclusions have been reached by different authors for the various 
forms examined, and the same author has not unfrequently changed 
his view when he came to study different material. From the excel- 
lent comparative studies of Monrcomery (48) and work done later, 
it is possible to summarize the essentials of the most important views 
as follows. 
ZACHARIAS (88) proposed the theory that the nucleolus contains 
no chromatin, after FLEMMING’s conclusion (33) that there were chemi- 
cal differences between true nucleoli and the chromatin reticulum. 
This view has been followed by various authors, who have concluded 
that there is no relation between the formation of chromosomes and 
the disappearance of nucleoli. This seems to be the condition in 
Polysiphonia. 
STRASBURGER (72, 74) published the view that the substance of 
the nucleolus is utilized for spindle formation, which conclusion was 
drawn from the fact that the nucleolus in many forms disappears 
partly or completely, immediately preceding the formation of the 
spindle. Later NEMEC (54) suggested that the disappearance of the 
nucleolus and the formation of the spindle may be regarded as two 
independent events, which take place simultaneously. STRAS- 
BURGER’S view has been followed by FarRcHILD (26), HARPER (38), 
Witiiams (81), and-others. The spindle formation of Polysiphonia 
will be considered in the next section under the heading “spindle 
formation.” 
STRASBURGER (70), however, formerly held the view that the 
nucleolus was reserve material serving to build up the chromosomes. 
This theory has been followed by PritzNER (59), GUIGNARD (37), 
FARMER (29, 30), SARGANT (67), SWINGLE (76), CARNOY an 
LEBRUN (13), CHAMBERLAIN (15, 16), DUGGAR (25), - ANDREWS 
(5), Morttrer (52), CavARA (14), WAGER (80), and others. 
