Embryo of Sciadopitys verticillata. 415 
and continues its growth until the neck-cells are reached. Meantime, the 
body-cell descends and takes up a position in the tip of the tube, and here 
undergoes division, giving rise to the two sperm nuclei. The tip of the 
tube apparently passes between the neck-cells, and its contents are dis¬ 
charged into the upper cytoplasm of the egg. The course of the tube 
in its passage through the archegonial chamber is shown in Fig. 48. 
Before and during the fertilization period the cytoplasm of the egg 
becomes heavily charged with coarse granules of food substance and 
numerous large so-called ‘ proteid vacuoles ’. Meantime, the nourishing 
jacket cells undergo a curious modification to which Arnoldi (’01) has 
called attention. The inner wall of these cells—that is, the wall lining the 
egg-cell—becomes strengthened by coarse, irregularly branched, reticulated 
thickenings. These thickenings project beyond the surface of the cells, and 
in sections may be seen extending into the cytoplasm of the egg. It 
would seem that there was a necessity for strengthening these walls without 
interfering with the transfusion of substances from the jacket cells into the 
egg. The thickenings were evidently not of cellulose, for they stained 
black after being treated with Flemming’s triple stain. They are probably 
of a chitinous nature. In surface view they appear as in Fig. 51. 
When the egg-cell is ready to be fertilized its nucleus lies in the centre 
of the cell just above the vacuole, as indicated in Figs. 44 and 48. The 
relative size of the egg nucleus and sperm nucleus may be observed in 
Fig. 49, the former being many times the size of the latter. Although the 
two male nuclei enter the egg, only one of them—presumably the larger 
one—unites with the female nucleus. The actual fusion of the sex nuclei 
was not observed, but the immediate result is shown in Fig. 50. Here we 
see the first spindle of the sporophyte organized within the boundary of the 
membrane of the egg nucleus. 
The Embryo. 
The position of the first cleavage spindle seemed to vary within the 
area of the fusion nucleus. The long axis of the spindle was sometimes 
found parallel to the long axis of the archegonium ; in others it was at right 
angles to this position. In Fig. 50 it is lying obliquely. There seemed 
to be no definite polarity in this respect. 
Before this first mitosis is complete the membrane of the fusion nucleus 
fades and finally disappears, leaving the two first free nuclei of the pro¬ 
embryo in the cytoplasm just about the middle of the egg. A sufficient 
number of stages of the spindle were found to observe with fair accuracy 
the number of the chromosomes, which were found to be sixteen. I was, 
however, unable to distinguish a male and female group which have been 
described by Miss Ferguson (’ 04 ) in the case of Pinus. 
The first two free nuclei remain in the middle region of the egg until 
