Development of the Embryo-sac and Embryo of Castalia odorata 
and Nymphaea advena * 
OQ By MELVILLE THuRsTON Cook 
(With PLATES 12 AND 13) 
The systematic position of the Nymphaeaceae has long been 
an unsettled question, since the family presents some characters of 
both monocotyledons and dicotyledons. The purpose of this 
study was to reach some satisfactory conclusion as a result of ob- 
servation on the development of the embryo-sac and the embryo. 
Castalia odorata Dryand, and Nymphaea advena Soland, were 
Selected and the study has shown that they differ in very few and 
minor points in their development. Since beginning these investi- 
gations, Lyon has published “Observations on Embryogeny of 
Nelumbo ”’ (9) in which he reaches the conclusion that it is a true 
Monocotyledon in which the single cotyledon bifurcates, thus giv- 
ing rise to the two fleshy bodies. 
The material was killed and fixed in Flemming’s osmic-chromo- 
acetic solution and in chromo-acetic. It was then washed, passed 
through alcohol, imbedded in paraffine and cut with Minot micro- 
tome. The stains used were haematoxylin and iron alum, safranin 
and gentian violet, and cyanin anderythrosin. The first and second 
combinations were especially successful. The safranin and gentian 
violet was especially good for demonstrating the antipodals. A 
large number of slides were prepared and most of the points 
figured were observed many times. 
DEVELOPMENT OF THE MEGASPORE AND EMBRyO-SAC 
The archesporial cell develops from the hypodermis and is 
easily distinguished from the surrounding cells. In one instance 
two archesporial cells were observed. The archesporial cell 
Snlarges (fig. 7 ) and the first tapetal cell is formed by a transverse 
division (fig. 2). Other tapetal cells are formed in a very ir- 
Fegular manner as a result of the division of the first. Two 
ae eS AS 
Contributions from the Botanical Laboratory, Ohio State University. 
211 
