In the German edition of Sollier’s book Professor Pelman, whom we have above mentioned, has written an introduction in which he speaks of the work in words of praise similar to those expressed by Lucien Arréat in _The Monist_. “Sollier,” says he, “has put us into the possession of a psychology of mental imbecility, in a completeness in which hitherto it was not at our disposal.” Then follows another passage which we will also quote, as it forms an important supplement to the remarks of Arréat. It is this: “Imbecility had remained the step-child of the science of psychiatry and has not by any means met with the consideration which in view of its social importance is due to it. If we go through the works, as great in number as they are in voluminousness, which have been published in the style of Lombroso on criminals and their peculiar characteristics, we shall be unable to escape the impression produced in our minds that the characteristics of imbeciles portrayed by Sollier recur point for point in the typical criminal. Here as there, the same insufficiency of all ethical development, the same frivolity, and the same incapacity for being of use in society exist. That which in Sollier’s explanation decides the whole anthropological position of the imbecile—his anti-social, society-hostile attitude—is emphasised by all writers as the characteristic trait common to all criminals, and the description of imbeciles and criminals coincides as completely in this respect as if the same individual had sat for both pictures. The conclusions that follow from this can only enlist new adherents in the ranks of the anthropological school, and this result also I should place to the profit-account of the present book.” However profitable and necessary employment with the diseased states of the human soul may be, personally at least it is an unpleasant subject for us, and we are glad therefore that we may abandon this domain for the present letter. The occasion of this is afforded by a valuable gift from Prof. W. PREYER, formerly of Jena, now of Berlin. Professor Preyer has presented us with a rather large volume bearing the title _Wissenschaftliche Briefe von Gustav Theodor Fechner und W. Preyer. Nebst einem Briefweschsel zwischen K. von Vierordt und Fechner sewie mehreren Beilagen. Mit dem Bildnisse Fechner’s und vier Holzschnitten_. Hamburg und Leipsic, 1890. Verlag von Leopold Voss. The work contains a correspondence extending from the year 1873 to the year 1883, in which the two distinguished scientists discuss (chiefly) myo-physical and psycho-physical questions, and will be of great interest to many readers of _The Monist_, especially as it makes its appearance simultaneously with the issuing of a new edition of Fechner’s _Elemente der Psychophysik_ by Wilhelm Wundt.