Vol. 50 No. 4 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
APRIL, 1923 
A study of the embryo sac development and accompanying 
phenomena in Oenothera rubrinervis 
CLAUDE E. O’NEAL 
(WITH PLATES 5 AND 6 AND TWO TEXT FIGURES) 
Since the announcement by De Vries at the beginning of 
the present century that Oenothera Lamarckiana was giving rise 
to new species by a process of mutation, the genus Oenothera 
has been subjected to a most thorough examination from al- 
most every angle of botanical science. It has been a special 
favorite with the plant geneticists, and the morphologists and 
cytologists have found in its changing species a source of ab- 
sorbing interest which has been maintained to the present time. 
The notable cytological work of Gates (14), Lutz (20), and 
Davis (5, 6) on the members of this genus was confined for the 
most part to the microsporocytes and root-tips of the species 
studied. The last mentioned, however, as well as Geerts (15) and, 
more recently, Ishikawa (17), touched upon the reduction divi- 
sions of the megaspore mother cells. As has been pointed out 
by Gates in this monograph and in other papers, the technical 
difficulties encountered in such a study are responsible for our 
* present incomplete —— of this phase of the life cycle in 
the genus Oenothera 
The present paper has to do with the development of the 
embryo sac and attending phenomena of ovule development and 
fertilization in Oenothera rubrinervis. The first study of the 
embryo sac in Oenothera was made by Hofmeister (16) almost 
three quarters of a century ago. One of his figures shows the 
course of the branched pollen tube through the thick nucellar 
[The Butterin for March (50: 95-132. pl. 4) was issued March 16, 1923.] 
133 
