ade a preliminary examination of the catkins from
your hickory tree received last May, and it seems that the
individual staminate flower of the catkin produces 4-5 undersized
stamens, the anthers of which are devoid of either pollen or
pollen-mother-cells. So far I have made only temporary preparations
of the crushed anthers in stain but careful study of these mounts
discloses no sign of pollen grains or mother cells, so we may
tentatively conclude that no pollen is produced by the tree; in
other words it is male-sterile. The stage at which degeneration of
the pollen-forming tissue occurs in the anthers and its nature will
have to be determined by means of a longer and more elaborate
technique and I will let you know what we find as soon as the
results are available. It may be that pollen-mother-cells are not
even formed in the anthers; the small size of these structures and
their more or less shriveled appearance lead me to believe that
this may be the case.

"So far as I know there is no instance among nut species comparable
to that outlined above. We have two or three cases of male
sterility in chestnut but in these no stamens are formed in the
individual staminate flower. In one of the hybrid walnuts that I
reported on at the Hershey convention, imperfect pollen grains are
formed in the anthers but the latter structures never open, so no
pollen is shed.

"Bear in mind that the above report is preliminary and other
angles may turn up when permanent mounts are available for study."

On December 14, 1943 I received a second, and final report from Dr.
McKay from which I quote, as follows:

"Dear Mr. Weschcke:

The enclosed pencil sketches will give you an idea of the results
obtained from sectioning four lots of material from the two samples
of catkins that you sent, two lots from each sample. Since the
sample collected May 25 at the time of catkin fall was old enough
to contain mature pollen and showed only anthers of the two types
described herewith I think we may safely conclude that the tree is
male sterile because of the failure of the mother cells to
function. It is odd that in some anthers the pollen-mother-cells
develop (type 2) while in others they do not (type 1). For this we
have no explanation; nor can we explain why the tree is ma