PECULIAR STRUCTURES OCCURRING IN THE POLLEN 
TUBE OF ZAMIA. 
HERBERT J. WEBBER. 
(WITH PLATE XL) 
THE recent announcement by Hirase* of the occurrence of 
motile spermatozoids in Ginkgo biloba, and that by Ikeno? of the 
occurrence of similar organs in Cycas revoluta, render any obser- 
vations on the phenomena occurring in the pollen tube of Zamia, 
belonging to the related sub-family Zamiez, of special interest. 
In cones of Zamia integrifolia shortly before fecundation the writer 
has observed several remarkable structures, which, so far as can 
be learned, have never been described. 
For a considerable period preceding fecundation in Zamia, as 
in many other gymnosperms, the pollen tube apparatus remains — 
in almost the same condition. no important changes taking place. 
In this stage the pollen grains, which lie in the pollen chamber 
at the apex of the nucellus, are found to have germinated and 
the germ tubes to have reached a length of 1 to 2™™, penetrating 
into the tissue of the nucellus. _ The pollen tube is much greater 
in diameter than the pollen grain which may be clearly distin- 
guished. The vegetative nucleus of the pollen grain, in every — 
case observed, has wandered into the pollen tube and may usu- 
ally be found near its lower end (fig. 7). In the upper end of 
_the pollen tube, near the pollen grain, two cells are uniformly 
found, one in close connection with the old pollen grain from 
which it protrudes or is only slightly separated, and the other 
_ immediately in front of this in the more swollen portion of the | 
a pollen tube (Fg. r). The former cell is oe or — 
se _ * Hrrase RASE, S.— Untersucliung ber das V. halten des Pollens von Ginkg bilob: 
Bot. Central. 693 33. Veto Ja. 1897. SEO ie 
Bot Centra, 69: i 30D. _ Se 
1897]. 
