86 
The Ohio Naturalist. 
[Vol. IV, No. 4 , 
passes in its development from ortliotropous, tlirough the anatro- 
pons condition and becomes campylotropous when mature. The 
setting aside of the lower endosperm nuclens of the first division 
by a wall and its development as a large vesicular cell, as is the 
case in Sagittaria and Vallisneria, while not confined to the Helo- 
l^iae nor apparently’ characteristic of all of them, is yet significant 
when one finds a similar peculiarity in some of the Xymphaeaceae. 
The number of ovules in the carpel also shows a diverse devel- 
opment. In Potamogeton, Alisma, Sagittaria and Xelumbo there 
is usually a single ovule in each ovulary. In Butomus, A^allisneria 
and other genera of the Plydrocharitales the ovules are scattered 
on the inner surface of the ovularies. This is also one of the 
striking characters of Xymphaea and Castalia. In fact the pecu- 
liar way" in which the ovularies of certain Xymphaeaceae agree 
with many of the Hydrocharitales must appear most interesting 
to anyone who has made the comparison. Coalescence and 
epigyny also figure in both the Hydrocharitales and Xymphaea- 
ceae. Thus it will appear that what might be cou.sidered as minor 
or secondary’ characters do not detract but rather add considerably 
to the weight of the argument that the Xymphaeaceae have very- 
much in common with the Helobiae. 
The important investigation of Lyon shows conclu.sively that 
he was correct in claiming that the embryo of Xelumbo is essen- 
tially of the “ Monocotyl” type, and, since there can be no ques- 
tion of the facts, it also appears that his further conclusion was 
unavoidable that the Xymphaeaceae should be placed near the 
Helobiae. As stated before, the writer had the opportunity of 
studying .some of Cook’s preparations and it became evident that 
the embryo of X'ymphaea advena is in all es.sentials similar to that 
of Xelumbo. Later a special study was made of the young embryo 
of Xymphaea advena. As stated by Cook, in the young embryo 
of Xymphaea the “cotyledon” is at first not lobed. Later there 
is a rapid development at the two sides resulting in a two-lobed 
structure (Figs. 14, 15). Since Conrad stated that in Ca.stalia 
odorata the embry^o has two distinct “cotyledons” from the first, 
a study was also made of this species. With .some difficulty very 
youug embryos were dissected out of their embryosacs which are 
easily removed from the ovule. It was found that although the 
“Dicotyl” appearance is quite strong, the embryo must be 
regarded as of the same type as Xynqdiaea and Xelumbo. In 
the vei'y young embryo there is an expansion which extends 
nearly around the base but is discontinuous at one side ( Fig. 16). 
.Soon this expansion develops on opposite sides as two prominent 
lobes in such a manner that the original connection between the 
two lobes is very difficult to distinguish (Fig. 17). On examining 
the embryo from below, however, the similarity to the Xelumbo 
aud Xymphaea embryos becomes perfectly apparent (Figs. 18, 
