. A contribution to the morphology and biology of insect galls [microform]. Galles (Botany); Galls (Botany). •9l»l Morphology and BtoLOCY of Insect Galls 335 lit a time, but occasionally the petiole of a leaf carrie* two or even thret and the miarib in rare instances two. The midrib galls are fairly regularly elliptical in outline with the shorter HU meter across the leaf. The swellings in most cases are nearly equally divided between the upper and the lower leaf surfaces. The petiole galls vary from spherical to ovoid in shape. In the latter case the smaller end of the gall ib towards the ape
. A contribution to the morphology and biology of insect galls [microform]. Galles (Botany); Galls (Botany). •9l»l Morphology and BtoLOCY of Insect Galls 335 lit a time, but occasionally the petiole of a leaf carrie* two or even thret and the miarib in rare instances two. The midrib galls are fairly regularly elliptical in outline with the shorter HU meter across the leaf. The swellings in most cases are nearly equally divided between the upper and the lower leaf surfaces. The petiole galls vary from spherical to ovoid in shape. In the latter case the smaller end of the gall ib towards the apex of the leaf. Dimensions of the gall:—Longer diameter 6-ia mm.; shorter dia- meter 3-7 mm. The very marked proliferation of tissue in this gall is not accompanied by a differentiation that presents many points of interest. The cells are larger than those of the normal leaf and the nuclei are correspondingly larger. The bundle is cut nearly through by the ovipositor (Fig. 8a). The free ends of the bundle thus stimulated grow out until in some cases they almost surround the gall. This elongation is produced in part by the increased diameter of the vessels but also by the production of new cellular elements. The pith, exposed by the cutting of the bundle, produces almost all the abnormal tissue (Figs. 83, 84), but the cortex contributes some. The cells are arranged in curved lines that pass across from one elon- gated end of the bundle to the other. Between these rows are many air spaces which are elongated in the direction of the lines of cells (Fig. 84). Undescribed Sawfly Gall on Salix humilis rifr i.—Lml o( tin hoM wiU> atUelMd fiU. This is a monothalamous gall produced by the abnormal swelling of the leaf petiole of S. hu nilis. It is conoidal in shape with a long taper- ing apex which is towards the blade of the leaf. As it is situated at the base of the petiole the uniform enlargement of that organ is often pre- vented by the axillary bud. This causes the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectgallsbo, bookyear1912
