THE REDUCTION DIVISIONS IN THE POLLEN MOTHER 
CELLS OF OENOTHERA FRANCISCANA 
Ralph E. Cleland 
(Received for publication December 24, 1921) 
Introduction 
Investigation of the Oenotheras has reached such a stage that it is 
essential, if any progress is to be made in the study of the group, to obtain 
species concerning the purity of which there can be no question. Of all 
the species so far studied, Oe. francisca?ia seems to give the most promise 
of being undoubtedly pure. This is a far western species, which was first 
described by H. H. Bartlett in 1914. His description is based on material 
grown at Washington for the first time in 1910, from seed collected at 
Carmel Beach, California, in 1905. Seed from this strain was sent to Dr. 
.B. M. Davis in Philadelphia, and grown by him under the name of Oe. 
franciscana B., which race he has carried on in selfed line since 191 3. This 
strain has proved to be very stable. It has never thrown any mutants, 
has shown a high percentage of pollen and seed fertility, and in every 
respect acts like a well established pure race. It thus falls into a group 
with Oe. biennis L. and Oe. grandiflora Ait., which have also been shown 
to be very constant. The cytology of Oe. grandiflora has been worked out 
by Davis (1909) and has proved exceedingly interesting as revealing a 
very regular nuclear behavior during the reduction process, with a definite 
pairing of homologous chromosomes at diakinesis and the formation of a 
clear equatorial plate at the heterotypic metaphase. This uniformity in 
development is quite in contrast with what has been found to be the case 
in those Oenotheras which are less stable; and it therefore becomes of 
interest to examine the spore mother cells of the other stable species to 
determine whether they also may show the same regularity of development 
displayed by grandiflora. 
Material 
Collections were made by the writer during the summers of 191 9 and 
1920 in the gardens of Dr. B. M. Davis. A variety of fixing fluids were 
used. Of these, one of Allen's modifications of Bouin's solution (Bouin A) 
gave the best results, although strong Flemming with urea and maltose 
added (S.F.U.M.) yielded some fairly satisfactory fixations. 
Description 
An attempt was made to study carefully the telophase stages of the 
last archesporial mitoses, with a view to determining whether a definite 
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