Igit] SMITH—CLINTONIA 213 
of the polar nucleus. Whether or not fertilization occurs normally | 
in those ovaries which develop into fruit, I am at present unable 
to say, nor can I assign the cause of the large proportion of abortive 
flowers. Apparently it is not due to any imperfection in the 
microspore, which contains two normal nuclei and appears plump 
and healthy. 
An attempt to estimate the percentage of fertile flowers by field 
observation proved futile. An area producing 550 flowers was 
kept under observation and undisturbed, but all to no purpose. 
The flowers one and all were abortive, and two weeks after opening | 
had withered and fallen away, leaving only the shriveled pedicels. 
An attempt also was made to determine whether the sterility 
is due to imperfect pollination. A small number of flowers were 
artificially pollinated, but these like the others yielded no seeds. 
However, as several days of heavy rain interfered with the experi- 
ment, I cannot regard it as conclusive. 
Discussion 
The interpretation of the embryo sac of Clintonia is made 
easier by recent investigations of certain Onagraceae. GEERTS 
(6) finds that in Oenothera Lamarckiana the single archesporial cell 
gives rise to a tetrad row of megaspores, of which the uppermost 
develops, slowly absorbing the three lowermost and producing 
four nuclei arranged much as in Clintonia. The same condition 
is reported by MopILewskKI (10) as occurring in Epilobium angusti- 
folium, E. Dodonaei, Oenothera biennis, and Circaea lutetiana; in 
all these the unipolarity of the embryo sac is strongly marked and 
there is ‘‘double fertilization.’’ A comparison of the embryo sac 
development of these and of Clintonia makes it clear that the four 
nuclei of figs. 5-7 represent four megaspores. Further, in these 
six species the unusual condition prevails of having the upper 
megaspore fertile. The chief differences shown in the development 
of Clintonia are in the absence of walls separating the megaspores 
and in the large proportion of sterile ovules. 
A nearly similar embryo sac occurs in Oenone and Mourera, 
two genera of the Podostemaceae examined by WENT (14). A 
mother cell after synapsis divides into two; the upper of these 
