Dr. Kühn’s paper on the crystalline schists treats principally of gneiss, and offers little that is new. It is mostly occupied with additional evidence of structural and chemical changes due to dynamic metamorphism in the sense of Lehmann. The most noteworthy of these are development and microstructure of fibrolite; production of augen-gneiss from porphyritic granite; development of microcline structure in orthoclase by pressure; secondary origin of microcline, microperthite and micropegmatite; alteration of garnet to biotite and hornblende. Dr. Sabersky’s paper on the coarse-grained granites or pegmatites is entirely mineralogical, and is devoted principally to elucidating the structure of microcline. The author concludes that the well-known gridiron structure is due, not to two twinning laws (the Albite and Pericline), as has been generally supposed, but to the Albite law alone, in accordance with which the individuals form both contact and penetration twins, like the albite crystals from Roc-tourné, described by G. Rose. Dr. Romberg’s paper on the Argentine granites is much more extensive than the two preceding. It is embellished by seventy-two microphotographs, many of which admirably illustrate the special points described. He comes to several results of great petrographical significance, the most important of which relate to the origin of quartz-feldspar intergrowths in granitic rocks. He clearly shows that beside the original granite quartz there is also much of a secondary nature present. This is not microscopically distinguishable from the original mineral, but its later genesis is demonstrated by many careful observations on its relation to other constituents. The abundant secondary quartz is regarded as the product of weathering--principally of the feldspar, into which it has a peculiar tendency to penetrate. The extreme sensitiveness of quartz to pressure is emphasized (as it has been by Lehmann and the present writer) and illustrated by undulatory extinction, banding, granulation and even plastic bending around other minerals. Dynamic action is regarded as the efficient cause of the secondary impregnation of feldspar by quartz, and a union of this with weathering of the feldspar as the source of the abundant and complex pegmatitic intergrowths of quartz and feldspar.