1897] THE POLLEN TUBE OF ZAMIA 457 
The writer has been unable to determine the origin of the 
centrosome-like bodies described above, and thus cannot be sure 
as to their nature. In the resting condition of the generative 
cell (fig. 3) they are somewhat similar to the bodies described 
by Hirase as “attraction spheres’’3 in the pollen cell of Ginkgo 
biloba, but his description and figure differ from what I have seen, 
in that spherical bodies much larger than the attraction spheres 
are located between them and the nucleus. No indications of 
the latter body occur in Zamia. The nucleus, furthermore, is of 
very different shape from those occurring in my slides of Zamia, 
and the so-called attraction spheres are apparently much smaller 
than the similar bodies which I find. 
The researches of Farmer,+ Osterhout,5 Mottier,© and Stras- 
burger7 have thrown much doubt onthe occurrence of centrosomes 
in the pteridophytes and phanerogams, where the nuclear spindle 
in its earlier stages is multipolar, at least in the spore or pollen 
mother cells. In view of these facts their occurrence in Ginkgo 
and Zamia may well be doubted. The spheres in the generative 
cell of Zamia resembles centrosomes in that they have the kino- 
plasmic filament centered upon them during a large part of their 
existence, and have an important relation to the formation of the 
spindle, being uniformly located near the poles and always hav- 
ing a definite orientiation with reference to the axis of the spin- 
dle. They differ, however, so materially from the centrosomes 
described by Farmer,’ Swingle,? Strasburger,* and others, and 
3 HirnaseE, S.— Notes on the attraction sphere in the pollen cells of Gindgo biloba 
The Botanical Magazine 8:359. 1894. 
*FaRMER, J. BRETLAND.— Ueber et in Lilium-Antheren besondersin 
_ Bezug auf die Centrosomen-Frage. Flora 
_ SOsTERHOUT, W. J. V.— Ueber Enstehu karyokinetischen Sp es qui-- 
setum. Jahr. £. wissenschaft. Bot. jo: 159. 1897. 
®Mottier, Davip M.— Beitrage zur Kenntniss der Kerntheilung i in den Pollen- 
Bot. 
Olgas einiger Dikotylen und Monokotylen. Jahr. f. wissenschaft Bot, go: 169. 
; 7 STRASBURGER, Enea Dae 2 igarRRENEN DS Kern- ond Zelitheil- 
ung, Jahr. f. wissenschaft. Bot. 30 : 375 1897. 
-- ® Farmer, J. BRETLAND.—On spore formation and nuclear division | ins the 
— er leg 469. 1895. 
