156 ANDERSON: EMBRYOGENY OF MARTYNIA LOUISIANA 
into the lower portion of the embryo-sac, where the first division 
takes place. The development of the embryo proper is like 
that of Capsella. 
I take opportunity here to express my obligations to Pro- 
fessor H. W. Anderson for the use of the Wabash College Bot- 
anical Laboratory during the summers of 1915 and 1916 and to 
Professor D. M. Mottier for valuable assistance and criticism 
in connection with this study. 
INDIANA UNIVERSITY 
LITERATURE CITED 
1. Billings, Frederick H. Beitrage zur Kenntniss der Samenent- 
wickelung. Flora 88: 253-318. 
2.Kanda, M. Field and laboratory studies of Verbena. Bot. 
Gaz. 69: 54-71. pl. 6-9 + f. 10-17, 27, 54-63, 09-75. 1920. 
3. Merrell, W. D. A contribution to the life history of 
Silphium. Bot. Gaz. 29: 99-133. pl. 3-10. 1900 
4. Mottier,D.M. Fecundation in plants. Carnegie Inst. Wash- 
ington Publ. 15. rg04. 
5. Oliver, F. W. On the structure, development, and affinities 
of Trapella, Oliv., a new genus of Pedalineae. Ann. 
2: 75-115. pl. 5-9. 1888 
— of plates 7 and 8 
PLATE 7 
All figures, X 400 
Fic. 17. Vertical section through the nucellus; megaspore mother-cell 
shaded. 
Fic. 18. Elongated nucellus with megaspore mother-cell; beginning of 
integument, I. 
Fi rtical section of young ovule turned on its axis; the integu- 
ment reaching half the length of the nucellus. 
Fic. 
20. Nearly mature megaspore mother-cell enclosed in a single 
layer of nucellus. 
FIG Heterotypic soit in megaspore mother-cell. 
1G. 22. Tetrad, the upper three potential megaspores disorganizing. 
Nutritive jacket formed from fis layer of integument adjacent the nucellus. 
F Section of young ovule showing the single integument and 
first division of the megaspore; the upper three potential megaspores dis- 
organizing. 
Fics. 24 and 25. Further development of the megaspore; the central 
portion of wate disorganizing. 
iS 
Loa) 
. 
