The origin and distribution of the genera of the fishes of South America west of the Maracaibo, Orinoco, Amazon and Titicaca basins / by Carl H. Eigenmann. Growth in trees / by D.T. Macdougal. The action of bases and salts on biocolloids and cell-masses / by D.T. Macdougal. The fixed glacial anticyclone compared to the migrating anticyclone / by William Herbert Hobbs.