[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 too weak. Finally he succeeded in grafting a branch from an affected tree on to a branch of a normal individual. The only result was an increased vigor of the healthy branch. This year he rubbed juices from leaves of such an abnormal individual on to wounded healthy leaves, without result. Moreover, such sick individuals, although growing for years close to healthy trees, have never communicated the malady to their neighbors. Growth is comparatively slow, and there is much dying back or dying out of the slender branchlets. The evidence indicates that this is _not_ a virus trouble, but a systemic defect, probably caused by chromosome aberration or gene abnormality. It is significant that this trouble occurs only in hybrids. Such trees never flower. We have known four such cases, two of which are now dead. Similar types appear in other species as inherited deviations from normal. Insect Injuries