Sa a a i ar hl kk okll 
IS Re Oe ee eed ig hae tet er ee eT a eer Pe eee 
1909] BRIEFER ARTICLES 59 
mentous suspensors. SEATON’Ss observations on the embryo of Nymphaea 
advena coincided with my first paper on this subject. 
In these later studies I have found that the embryo of Nymphaea advena 
originated (fig. 12) and develops in the same manner as _ previously 
described by me, but that in some instances the latent suspensor is almost 
or quite as prominent as in the Cuban form. In Castalia odorata I found 
both types of embryos described by me in my first paper; i. e., without a 
suspensor (jig. 13), and also with a suspensor (fig. 14), as described by 
Conarp and by myself in my paper on the Cuban Nymphaeaceae. These 
recent studies on Nelumbo lutea showed in most cases a spherical embryo, 
without a suspensor, and agreed fully with the observations of Lyon and 
York, but in one or two cases there appeared a small suspensor (fig. 10) 
of the same type as described for Nymphaea advena, except that it appeared 
somewhat earlier in the development of the emb 
Recent studies on Castalia odorata and N ymphaea advena confirm the 
previous observations of myself and others on the formation of a cotyle- 
donary ridge, from which the two cotyledonary lobes are developed. 
The studies referred to in this paper convince me that the species of 
Nymphaeaceae are either very plastic and subject to considerable variation, 
or that we are confusing very closely related forms. 
SUMMARY 
1. Extra embryo sacs are frequently formed. 
2. The cross-wall between the two daughter nuclei, which are formed by 
the first division of the endosperm nuleus, is usually present, although so 
delicate that it is very difficult to demonstrate. 
3. The nucleus in the micropylar end of the sac forms the endosperm. 
4. The nucellar tube is somewhat different in the different species, and 
also subject to great variation, especially within the genus Castalia. 
5. The embryo of Nymphaea originates without a suspensor and later 
develops a latent suspensor; the embryo of Castalia originates either with- 
out or with a filamentous suspensor; the embryos of Cabomba and Brasenia 
with short filamentous suspensors; and the embryo of Nelumbo either with 
or without the very short latent suspensor.—MEL. T. Cook, Delaware 
Agricultural Experiment Station, Newark, Delaware. 
EXPLANATION OF PLATE VI 
Abbreviations: ¢ embryo; ¢ tube nucleus; » egg; s synergids: a antipo- 
wall. 
_ dals; w cross- 
Fros. 1~7.—Diagrams of ovules, showing sac and nucellar tube: jig. J, 
: Nymphaea advena; figs. 2, 3, Castalia odorata; figs. 4, 5, Castalia ampla; fig. 6, 
4 Brasenia and Cabomba; fig. 7, Nelumbo lutea. 
