1912] CHAMBERLAIN—CERATOZAMIA 19 
EXPLANATION OF PLATEI 
(Figs. 1-7 are text cuts) 
Ceratozamia mexicana 
Fic. 8.—Pollen grain beginning to germinate in a sugar solution; beneath 
the tube nucleus is the generative cell which is to produce the stalk and body 
cells; beneath this and resting upon the intine is the single persistent prothallial 
cell; the spherical bodies are starch grains; 730. 
Fic. 9.—Like the preceding figure, but there has been some plasmolysis, 
and at ie right side of the figure, toward the top, the intine has pulled loose 
from the exine; 730. 
Fic. 10.—Germinating pollen grain drawn from living material; 730. 
Fic. 11.—Nucellus and part of female gametophyte with archegonia; the . 
pollen tube at the right shows the primary haustorium just beneath the upper 
surface of the nucellus, and farther down, opposite the body cell, a branching 
secondary haustorium; the lightly dotted area above the archegonia represents 
the liquid filling the archegonial chamber and pressing up the megaspore mem- 
brane, represented by the dark line; X14. 
Fic. 12.—Nucellus at a later stage showing behavior of secondary haus- 
toria; X14. 
Fic. 13.—Pollen tube which would have produced four sperms; a single 
unbranched secondary haustorium extends obliquely downward; X 130. 
Fic. 14.—Two young sperm mother cells showing the remnants of the 
broad spindle and the ciliated band just beginning to form; X 180. 
Fic. 15.—Two sperms about to escape from their mother cells; 130. 
Fic. 16.—Mature sperm; 180 
Fic. 17.—Part of archegonial chamber and upper part of the archegonium, 
showing the small ventral canal nucleus and the egg nucleus; X25. 
Fic. 174¢.—Detailed drawing of the ventral canal nucleus shown in the 
preceding figure; 475. 
Fic. 18.—Megaspore membrane with parts of two adjacent endosperm 
cells; X833. 
Fic. 19.—Free nuclear stage of proembryo; the sheath and ciliated band 
of the sperm are shown at the top; X27. 
Fic. 20.—One embryo formed by the fusion of four; the fifth embryo 
stopped developing part way down the suspensor igre Mieg. 
Fic. 21.—Three suspensors with two embryos; X1.5. 
Fic. 22.—Each suspensor has an embryo at its tip; X1.5. 
Fic. 23.—Young embryo showing irregular outline of an embryo formed 
by fasiod of two or more embryos; X1. 5. 
