1912] PFEIFFER—LEITNERIA 195 
was especially true of the tissue at the chalazal end, which was a 
very loose tissue and contained large, irregular nuclei, which were 
possibly produced by the fusion of several nuclei. 
The embryo 
After free nuclear division had continued for some time in the 
endosperm, the division of the fertilized egg occurred. The first 
two-celled embryos seen were in material which was killed April 
30. It was a matter of indifference in which plane the first division 
wall should lie, so that in some cases (fig. 8) the first wall was 
parallel to the longitudinal axis of the embryo sac, while in others 
the position was the horizontal one almost universal in the embryos 
of angiosperms. In whichever plane the first division occurred, 
other divisions followed rapidly in all planes, so that there was in 
no case a slender suspensor formed. In fact, in the young stages 
the embryo was somewhat pear-shaped, with the massive suspensor 
only slightly narrower than the body of the embryo (fig. 9a). 
The growth of the embryo, and indeed of the whole fruit, was 
very rapid. Figs. 8a, 9a, and 10a, which were drawn to the same 
scale, show the increase in size of the embryo itself within the first 
five weeks. Fig. 9 shows the detail of a few cells of the endosperm 
and the outermost layer of cells of the embryo at the micropylar 
end of the embryo sac. It will be noticed that at this stage, when 
the embryo consisted of a relatively large number of cells, there 
was as yet no evidence of the appearance of cotyledons (fig. 9a), 
the embryo proper still appearing as a globular mass of cells. 
Shortly after this, however, the cotyledons began to appear as 
protuberances from the distal end of the embryo, and within a few 
weeks there was the well-organized embryo as shown in the diagram 
(fig. roa.) Cell detail of the suspensor region of the embryo is 
shown in fig. 10, where it will be noticed in comparison with fig. 9, 
which shows some of the outer cells of this region, that there had 
been but slight increase in the size of the cells of this region. Fig. 
11 shows, under slightly less magnification than fig. 10, the detail 
of cell structure of the root end of the embryo and the lower por- 
tion of the suspensor. At this stage, examination even under low 
magnification showed a clearly defined periblem (fig. 10a). Under 
