ranous
perianth-segments for each tiny flower, whitish in color, and more or
less connected at their bases. A minute rounded mass appears in the
center of the flower, perhaps primordia of abortive stamens, but this
does not develop further. The catkin begins to take on a brownish color
and at length the whole catkin, in case it is staminate, drops off. If
it is androgynous, the staminate part drops off, or withers.

These male sterile trees appear to have a normal, sometimes excessive,
development of the females, and are quite prolific nut producers.
Information on the occurrence of female sterility in the hybrid trees is
incomplete, but the indications are that at least partial sterility is
frequent.

[Illustration: Fig. 5. A. Normal androgynous catkin (female flower at
base); B. Androgenous catkin with sterile pollen. From Sleeping Giant
Chestnut Plantation, Hamden, Conn. Photo by Mary Alice Clark, Conn.
Agric. Expt. Sta. July, 1949.]

2. _Triploid Hybrid_

In 1934 we produced a cross of Chinese and American chestnut which
proved to be unusual in several respects. The leaves are enormous--9
inches to 1 foot in length, and 4 or 5 inches in width. The hybrid is
not particularly blight resistant but more so than its American parent.
It died back from the blight about 1940 and the present tree has
developed as a shoot from the old roots. The growth is rapid and
vigorous. The flowers appear normal, but we have never been able to make
a cross with its pollen, nor to effect fertilization of its pistillate
flowers. It may be triploid, that is, with 3 sets of chromosomes instead
of the normal double set, and this would account for its barrenness.

In the spring of 1952 some of the vigorous shoots of this tree were
successfully grafted on shoots from an old stump of Chinese chestnut,
using the veneer crown graft method. The scions had not been taken when
dormant, but were transferred directly from the tree to the stock in
late April. This grafting was done in order to impart greater
resistance, if possible, to the CA hybrid by means of the roots of the
Chinese stock.

3. _Systemic Defect_

Since the early 1930's we have seen occasional individuals with abnormal
foliage--somewhat mottled, usually curled and often misshapen. Thinking
that a virus might be the cause of this trouble the senior author tried
grafting some of the shoots on to healthy stocks. The grafts were in no
case successful because the scions were to