-Tan., 1903.] 
Claytonia virginica. 
35i 
grows very rapidly and gives rise to the very large cotyledon 
(Fig. 19). This cotyledon grows very rapidly and curves into 
almost a complete circle (Fig. 22). The inner point of growth 
makes very little increase in size and forms the inner rudimentary 
cotyledon, which now appears as a small projection almost at 
right angles to the large cotyledon (Figs. 19, 20, 21). 
The plumule originally stands at the upper end of the axis of 
the embryo (Fig. 18), but with the development of the large 
cotyledon it is pushed to one side, so that in the older stages it 
appears as a lateral plumule (F'igs. 19, 20, 21 ). 
The development of the calyptrogen begins in the dermatogen 
and in the cells just above the suspensor ( F'ig. 19 a), and gradu- 
ally extends across the tip of the embryo. The root cap is formed 
in the usual manner, by transverse division of cells in this layer, 
and about this time the suspensor begins to disappear. 
SUMMARY. 
1 . Normally four megaspores and two tapetal cells are formed, 
the lower megaspore cell forming the embryo sac in the usual 
manner. 
2. The first five or six divisions in the formation of the 
embryo are quite regular, but the succeeding divisions are very 
irregular. 
3. The suspensor is at first filamentous, but becomes massive 
by longitudinal divisions. It does not contribute to the forma- 
tion of the tissues of the root-tip. 
4. Only one cotyledon develops and it becomes very large ; 
the other cotyledon remains rudimentary and gives the mature 
embryo the appearance of a monocotyl. 
I wish to express my thanks to Professor J. H. Schaffner, of 
the Ohio State University, for valuable suggestions in the com- 
pletion of this study. I also wish to express my thanks to three 
of my former students in DePauw University, Mr. J. W. Uittle, 
Miss Nellie Inwood and Miss Helen Powell, for valuable material 
and preparations. 
