Patho-Physiological Studies on the Insect Gall of Distylium tacemosum S_<IEB>. Et Z_<UCC>. : I.Observation on the Process of the Gall Formation by Astegopteryx yanonis M_<ATSUMOTO>

On Distylium racemosum SIEB. Et ZUCC. Are usually found three kinds of insect galls:“Leaf Gall” formed by Astegopleryx yanonis MATS.,“Globular Gall” formed by A.globuli MONZ. And “Fig-shaped gall” by A. djstychii PERG. The gall formation process in the leaf gall by the causal aphid was observed by means of radiographs with the ultra soft X-ray apparatus and the microscope. A.yanonis MATS. Was found to lay eggs on or near the bud of the host plant. When the hatched stem-mother of the aphid settles down on the surface (usually on the under surface) of a young leaf, the part of leaf tissue which surrounds the aphid begins to grow rapidly. The cells of this hypertrophic portion continue to make abnormal overgrowth, and the part becomes round, and the modified leaf hairs abundantly grow on the edge of the surrounding wall of young gall tissue. In this way, the overgrowing abnormal tissue cells develop to from the typical globe-like gall in the leaf. Regarding the type of gall formation the gall in question seems to belong to the so-caned “Umwallungsgalle” according to KUSTER's classification.