5 
Embryo of Cephalotaxus drupacea. 
During the time that the pollen is free, there is practically no difference in 
the cellular contents of the grain of the winged pollen of the Abietineae and 
the wingless pollen of the majority of other Conifers. It thus seems to me 
that the correlation of the winged character of the pollen and the survival 
of the prothallial cells is not quite consistent. To my mind the survival of 
these latter structures is an indication of the primitive character of the 
Abietineae as a group. 
The discharge of the pollen in Cephalotaxus begins late in March and 
continues for about three weeks. A considerable difference in the time of 
pollination was noted from year to year, which was probably due to the 
variable seasons in California. When the pollen is shed, the megasporan- 
gium is but a very small pointed protuberance surrounded by a well- 
developed integument. The micropyle is a little longer than the sporan- 
gium, as shown in Fig. 3, and remains open for some time after pollination. 
The microspores become lodged on the top of the megasporangium at the 
base of the micropyle, and here they remain ; and although they enlarge 
considerably, there is not much further germination until the following 
spring. Early in May of the following year the pollen-tube becomes 
visible and begins its downward penetration into the tissue of the nucellus. 
In some cases there was observed a slight indication of the branching of 
the tube at this time, as shown in Fig. 4, but the main growth was always 
in a downward direction, directly toward the female prothallium. Previous 
to the penetration of the tube, the division of the generative nucleus takes 
place, for, as shown in Fig. 4, the body-cell is already organized, as well as 
the stalk-nucleus. The young tube now contains one large cell and two 
free nuclei, and in this respect conforms with the conditions met with at this 
time in most Conifers. The body-cell is distinctly oval in shape, and is 
surrounded by a distinct membrane. It contains a dense granular cyto- 
plasm and a large, deeply-staining nucleus, which is quite four or five times 
the size of the stalk or tube-nucleus. One constant character of the body- 
cell is that its long axis is parallel to the long axis of the tube, and that 
its large nucleus is invariably found near the cell-membrane, at the side 
away from the stalk and tube-nuclei, as shown in Figs. 4 and 5. The stalk 
and tube-nuclei show no perceptible increase in size as the tube advances. 
They are almost identical. Indeed, it is quite impossible, at this time, to 
distinguish the one from the other. They lie close together, imbedded in 
a mass of cytoplasm close to and always in advance of the body-cell. 
From this time on, the growth of the tube is comparatively rapid. The 
condition of the tube and its contents, shown in Fig. 4, was found on May ri, 
while that in Fig. 5 was found on May 21, taking just ten days for the tube 
to penetrate completely through the nucellar tissue and reach the arche- 
gonial chambers at the upper part of the female prothallium. The nucellar 
tissue, through which the tubes push their way, has a lacerated appearance, 
