Edited by D. T. MacDougal. Price, $5.00 net

The Mutation Theory

By Hugo De Vries

Experiments and observations on the origin of species in the vegetable kingdom. (2 vols.) Translated by Prof. A. B. Farmer and A. D. Darbishire. Numerous illustrations, colored plates. Cloth, per volume $4.00 net.

Intracellular Pangenesis

By Hugo De Vries

Including a paper on fertilization and hybridization. Translated from the German by C. Stuart Gager. Cloth, $3.00 net.

On Memory and the Specific Energies of the Nervous System

By Ewald Hering

New edition, including "The Theory of Nerve Activity." Price, $1.00; paper, 30c.