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PHILOSOPHICAL PERIODICALS. 441 ' circle of action ' on the retina, at any spot within which it may appear ; and as we are trying to fixate, we think that its appearance at different spots means movement.] W. A. Nagel. ' Ueber kompensatorische Kaddrehungen der Augen.' [Literature. Measurement methods : regular corneal astigmatism, after-images, blind spot. Experiments by last method ; proof of torsion. Preliminary report of work on animals, and comparison of certain animals with men.] E. Burmester. ' Beitrag zur experiinentellen Bestimmung geometrisch-optischer Taeuschungen.' [If two vertical parallels are cut obliquely by a transversal, itself not continued between the parallels, the two parts of the transversal appear not to belong together (Poggendortfs figure). The rule of the illusion is found to be as follows : The parallel displacement of the parts of the transversal is proportional to the distance separating the vertical parallels and the cotangent of the angle of inclination of the trans- versal ; the vertical displacement is proportional to the same distance and the cosine of the angle of inclination ; the angle of overestimation is dependent upon the angle of inclination and conditioned by the personal constant, but independent of the distance separating the vertical parallels. A similar rule holds for the figure obtained by reversing the direction of one of the parts of the transversal.] E. B. Titchener. ' Entgegnung.' [Reply to criticism of Heymans.] Litteraturbericht. Bibliographic der psycho-physiologischen Litteratur des Jahres 1895. [1588 titles.] PHILOSOPHISCHE STUDIEN. Bd. xiii., Heft 1. W. Wundt. ' Ueber naiven und kritischen Realismus,' ii. [This second paper is devoted to the empiric-criticism of Avenarius and his school, which professes to make experience the basis of all criticism of concepts, whether philosophical, scientific or prescientific. The writer gives an exposition (1) of the general theory of the school, translating its terminology into ordinary language ; (2) of the applications of the theory ; and (3) of the special hypothesis of introjection. He then passes to a critical discussion of the presupposi- tions of the system. It conflicts with positive natural science in its assumption that thought of the object always carries with it thought of the ideating subject. Its ' System C ' is really a metaphysical substance. Its reduction of quality to quantity is unjustified. Its ' objective ' consideration confuses the two meanings of ' objective,' impartial and abstracting-from-subject. Its actual methods are not those officially recognised : they are the methods of psychophysical analogies (principle of practice) and of a peculiar dialectic. Its professed methods, on the other hand, are not strictly followed : they are the methods of economy of thought and of pure description. The system confuses didactic, methodologic and metaphysical economy of thought, inclining however to the last. And its description involves explanation. A third paper will discuss the historical relations of empiric-criticism, and its attitude to natural science and psychology.] K. Marbe. ' Neue Versuche ueber intermittirende Gesichtsrei/e.' [As the difference between two stimuli increases, the duration of the critical period decreases, at first quickly, then more slowly. This holds whether the mean intensity increases or diminishes with increase of the stimulus-difference. It holds also for subjective differences, and without regard to the mean stimulus- intensities corresponding to them. The duration of the critical period is determined by the objective stimulus-differences : approximately equal periods correspond to equal objective differences.] M. Arrer. ' Ueber die Bedeutung der Convergence und Accommodations-bewegungen fuer