ee 
1893.] Embryo-sac and Embryo of Senecio. 251 
of the embryo into octants follow each other rapidly; for in 
different flowers of the same head, embryos as represented in 
fig. 13 were very frequently found along with those developed 
as far as shown in fig. 16 or farther. The stage figured in fig. 
14 was rarely met with. 
The usual form of the embryo at this stage of development 
is that which is figured in figs. 1%, 18, the figures repre- 
senting longitudinal sections. 
_ Each of the four upper cells of the embryo is now divided 
into two by anticlinal walls (fig. 16). Immediately following 
this each cell of the embryo is separated into an inner and 
outer cell by its periclinal wall (figs. 18, 21). The outer row 
of cells is the dermatogen or young epidermis; its cells divide 
henceforward only by walls at right angles to the outer sur- 
face, i. ¢., anticlinal walls, no periclinal walls being formed. 
the inner cells are the initial elements of the periblem and 
plerome, which are very early distinguishable from each other. 
's may be plainly seen in fig. 22, and in fig. 20, which is a 
aa itis of a young embryo. The cells of the periblem 
oh gece now divide by both longitudinal and transverse 
23) i tons being quite regular for a time (figs. 22, 
sisi (he ot embryo increases in size they become less reg- 
The cell divisions which take place in the cell x, fig. 14, 
ow with as great regularity as in Capsella. 
a age oF twice by transverse walls (figs. 18, 21, 23, 
walls, thou “os 's thus formed divide further by longitudinal 
any cell er “ie no great regularity (figs. 22, 24). Whether 
cell of the Pay S are cut off from the upper part of the large 
i oo could not be determined, as the nucleus 
Stated, it “a . Process of division. However, as above 
an "Dutes to both embryo and suspensor. 
Pensor consists of few cells, usually three or four, 
ng large and cylindrical, and projecting 
ropyle (figs. 18, 22, 25). In fig. 26 the 
= € cotyledons is seen; the limits of peri- 
8 € are indicated by heavy lines. Thus at 
ge of development those sans wwhickeare to become the 
otyledons are quite apparent (figs. 25, 26), 
Further g the development as represented in figs. 21, 
evelopment of the embryo was not followed. 
