DIVISION OF THE CENTRAL CELL. 47 
by the writer at the August 22, 1898, meeting of the American Asso- 
ciation for the Advancement of Science, and was published in Science, 
November 11, 1898 (127). The same conclusion as to the origin of 
the cilia-bearing band in Cycas was reached by Ikeno apparently about 
the same time, and published in his monograph which appeared some- 
what later, November 23, 1898 (70, p. 575). The beak which extends 
out from the nucleus to the blepharoplast and forming band in Cycas, 
as described by Ikeno in Cycas (70) and by Hirase in Ginkgo (62), 
the writer has not been able to find in Zama, even after renewed 
search. There would seem to be no reason, however, to doubt the 
correctness of the observations of Ikeno and Hirase. It may be that 
such a nuclear beak is formed also in Zamia, but was contracted in 
the writer’s specimens by the reagents. There is nothing to indicate 
this, however, and the writer believes that no such nuclear extension 
or beak is formed in Zama. How it could have escaped observation 
in the long-continued researches of the writer when special attention 
was given to searching for it is difficult to imagine. Similar beak- 
like extensions of the nucleus toward blepharoplasts have been 
observed by Strasburger (112) in swarm spore formation, and toward 
the centrosphere by Harper in the formation of the ascospore walls in 
Erysiphe (51, figs. 18-25) and Lachnea (52, figs. 48-45). In a late 
stage of the spermatozoid formation in Zama, when the ciliferous 
band has completed its growth, numerous little points have been 
observed extending out toward it from the nucleus, but these extru- 
sions are certainly not connected in any intimate way with the process 
of band formation. 
In the stage when the ciliferous band first begins to organize, the 
daughter nuclei are usually approaching a resting stage (fig. 36) and one 
nucleolus and sometimes two have already been organized ineach. The 
spindle fibers have shortened up materially and the cell plate is usually 
fairly well organized. ‘The formation of the plasma membranes sep- 
arating the two cells is frequently shown with great clearness in Zama 
and one can observe all stages of the transformation of the spindle 
fibers into the reticulum on one side and the plasma membrane on the 
other. The spindle fibers gradually shorten in length and contract 
into the cell plate, apparently forming the material for the organiza- 
tion of the separating membranes. Even in an early stage of the 
organization of the separating membrane, when only a few meshes of 
the cytoplasmic recticulum intervene between the daughter nuclei and 
the ends of the spindle fibers, the place where the future cell wall 
will form is plainly shown by a slightly lighter, clearer area crossing 
the cell (figs. 35 and 63). As the cell advances thickenings appear on 
the spindle fibers where the new wall is to form. The fibers continue 
to contract more and more until they become very short. A lighter 
staining mass of protoplasm then shows on each side of the forming 
