Feb., 1903 .] 
Agrostemma githago. 
3 6 7 
top divide again so as to form a quadrant (Fig. 14). The upper 
cell is the next to divide by a longitudinal wall (Fig. 15), and 
this is followed by a division of the fourth cell from the top 
(Fig. 16 ’. Repeated longitudinal divisions now result in the 
spherical embryo made up of five tiers of cells (Figs. 17, 18, 20). 
In the meantime the suspensor has elongated by transverse 
divisions, but the large basal cell remains unchanged (Figs. 18, 
20, 21, 22). 
This spherical embryo now enlarges by both longitudinal and 
transverse divisions in the different tiers until the appearance of 
the cotyledons, when it begins to elongate Figs. 21, 22 and 25 . 
The cotyledons develop in the typical dicotyl manner on oppo- 
site sides and at the summit of the spherical embryo, and with 
the plumule between. At the same time the calyptrogen begins 
to develop in the row of cells next to the suspensor, giving rise 
to a well-developed root-cap. The embryonic tissues are quite 
distinct : the dermatogen. periblem and plerome being easily rec- 
ognized. At about this time the suspensor disappears, and the 
embryo elongates and becomes very much curved in the embryo- 
sac, the inner cotyledon being slightly shorter than the outer one 
(Fig. 26). 
It will be easily seen that there is very little similarity between 
the development of the archesporium, the ovules or the embryo 
of Agrostemma githago and Claytonia virginica. the embryonic 
development being entirely different. The embryo of A. githago 
resembles in general appearance the embryos of Cruciferae as 
represented by Capsella and Alyssum. 
I wish to express my thanks to Prof. J. H. Scliaffner, of the 
Ohio State University, for many valuable suggestions in this study. 
CONCLUSIONS. 
1. The archesporium develops as one, two or three cells, of 
which all but one are absorbed. 
2. The sac is formed from the one remaining archesporial cell 
in the usual manner. After the formation of the eight-cell stage, 
the enlargement of the sac is from one side and at right angles to 
the original long axis. 
3. With the formation of the sac, the ovule enlarges from the 
micro pylar end, thus leaving the sac deeply embedded in the 
nucellus. A short beak is formed, which projects through the 
micropyle. Two or three rows of cells degenerate to form a 
passage for the pollen tube. 
4. The embryo is at first filamentous, the basal cell being very 
large. The four or five cells next to the apex divide longitudi- 
nall}’, forming the four or five tiers of a large spherical embryo. 
The cotyledons and the root-tip are formed in the usual dicotyle- 
donous method. Soon after the appearance of the cotyledons the 
suspensor degenerates. 
