262 • The Ohio Naturalist [Vol. VIII, No. 4, 



plasmic in appearance but rather consist of a radial arrangement 

 of ordinary cytoplasm. They do not lead to cell formation 

 although a small amount of endosperm persists until the seed is 

 nearly mature. 



After fertilization the egg elongates and forms a pro-embryo 

 four cells in length. There seems to be a more or less constant 

 transverse division in the second cell of the pro-embryo, thus 

 foreshadowing the massive suspensor (Figs. 8 and 9). The two 

 suspensor cells thus formed by division together with the basal 

 cell flatten against the wall of the integuments and give a foot- 

 like appearance to the base of the suspensor, and form a hausto- 

 rium like organ which maintains its activity, judging by its 

 staining reaction, till the embryo is mature, although the upper 

 cells of the suspensor may begin to break down before that time 

 (Figs. 10, 12, 16 and 17). This organ burrows its way into the 

 integuments until it reaches the testa forming a ball of tissue 

 which may, apparently from the division of the original three, 

 consist of a number of cells. The third cell of the pro-emb3^ro 

 probably forms the remainder of the suspensor consisting usually 

 of three tiers containing one or two rows of cells (Figs. 13-16). 

 The suspensor is rather short, forms no part of the embryo, has 

 no hypophysis as has long been known for Geranium,* nor does 

 it form the rootcap. As the embryo matures the dermatogen 

 and calyptrogen are extended around the tip of the hypocotyl. 

 The calyptrogen and calyptra are differentiated from this in the 

 usual way. With advanced growth they cornpletely surround 

 the hypocotyl and form the root cap (Figs. 15 and 16), which is 

 for a time distinctly concave at its junction with the suspensor 

 till that organ disintegrates and disappears. With this excep- 

 tion, the general development of the embryo is similar to the 

 Capsella type. The cotyledons arise from the opposite points of 

 the almost spherical embryo in the usual dicotyl manner with the 

 plumule between them. 



SUMMARY. 



1. The archesporium is a single sub-epidermal cell and 

 becomes the functional megaspore directly without forming 

 parietal tissue. 



2. The whole nucellus functions as tapetum. 



3. The antipodals and synergids disappear soon after 

 fertilization. 



4. The embryo forms no hypophysis. 



5. A multicellular haustorium-like organ is formed from the 

 basal cells of the suspensor which forces its way through the 

 integuments until it reaches the testa. 



* Coulter and Chamberlain, Murijliology of Angiosperms. 200. 190.3. 



