248 BOTANICAL GAZETTE [APRIL 
“central portion of the division-figure is a single strand which widens 
and becomes fibrillated at the ends.”” SCHAUDINN (:00, p. 229) eVi- 
dently does not so regard the corresponding portion of the dividing. 
nucleus in Coccidium, since he calls this connecting strand simply 
“Verbindungsfaden der Tochterkarysome,” and says that “von 
Spindlefasern und Poldifferenzirungen ist keine Spur wahrzuneh- 
men.” I am also inclined to believe that no part of the constricted © 
nucleolar body in Euglena and Coccidium is homologous with the 
central spindle of more complicated nuclei, since in all cases where a 
structure occurs which can be positively referred to the central spin- 
dle, it consists of usually distinct fibers which extend between and 
connect the diverging chromosomes. In these instances, the con- 
necting portion of the dividing nucleolar body bears no such relation 
to the chromatic filaments, but instead it lies simply as a slender core 
in the axis of the mitotic figure. Further, in the centronucleus of Em- 
pusa, which is undoubtedly similar in every respect except this one 
to that of Coccidium, such a connecting body does not occur at all, 
unless, indeed, it be represented in fig. 49. - Therefore, the strand 
connecting the constricted nucleolo-centrosome of Euglena and 
Coccidium, in my opinion, does not represent, phylogenetically, the 
central spindle, nor in fact any structure of the higher nuclei, but is 
a structure which is confined, so far as yet known, to these two Pro- 
tozoa. It is just what ScHAUDINN calls it, viz., simply a drawn-out 
filament connecting the daughter centrosomes, which has no appar- 
ent function. On the other hand Paramoecium, as shown in HERT- 
wic’s figures, shows a true central spindle, and the final median 
constriction of this spindle and the consequent aggregation of the 
bers of the middle portion into what appears to be a single strand, 
does not present a figure which can be in the least compared, as 
CaLkrns claims, with the nucleolo-centrosome described above. If 
there be any indication at all of central spindle in these simpler cen- 
tronuclei, then, in my opinion, it must be looked for in the dimly 
defined, continuous, bluish substance, for example, shown in the 
drawings of Coccidium (see SCHAUDINN’s figs. 31, 32), which lies 
between the daughter chromatin masses. SCHAUDINN himself, how- 
ever, evidently believes that these are not spindle fibers. In the case 
of Euglena, the central spindle is probably represented by the dim 
