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PHILOSOPHICAL PERIODICALS. 283- We must therefore assume ' recognition marks ' as prior to ' local signs '. The limen of direction (the least distance between stimuli that gives a certain judgment of their relative positions) is about twice as large as the successive limen.] E. von Oppolzer. ' Gnmdzuge einer Farbentheorie. r. Allgemeine Gruridlagen.' [(1) All our colour sensations are resultants of the fusion of at least two ' elementary sensations,' corresponding to an excitation of a single opticus fibre. The elementary sensations are not colour sensations (like the red, green and violet of the Helmholtz theory), but brightnesses. Their fusion gives differences of intensity and of com- position ; and these differences (cf. timbre in the tonal sphere) condition our actual colour sensations. Three such elementary sensations are adequate to account for the phenomena of colour vision. Colours are most saturated when the intensities of the three elementary sensations are as 1 : 2 : 3 (in dichromatic systems, when the two intensities are as 1 : 2). They thus owe their existence to an ' inne-e Gegensatzlichkeit ' of the three elementary intensities. (2) Colour perception : an attempt to correlate the three elementary sensations with structural differences in the outer members of the cones. (3) Fechner's Law : derivation of Fechner's constant ; influence of the idioretinal light ; relation of in- tensity of a mixed light to the intensities of its components.] J. Volkelt. ' Der aesthetische Werth der niederen Sime.' [We must dis- tinguish between the sensations which constitute the aesthetic object, and those which belong to the subjective attitude of aesthetic enjoyment or appreciation^ We must distinguish also between sensations actually present, and their reproductions. How far, now, do real sensations from the lower senses constitute or help to constitute the aesthetic object ? Opinions differ widely. It is clear that sight and hearing have two great advantages : they are less material, their stimuli do not directly involve a knowledge of bodily affection ; and they are sharply grouped, definitely and significantly arranged. Can the lower sensations, which lack these advantages, still play any part in the aesthetic impression ? Smell can, in natural and in artistic beauty (flowers ; the artistic arrangement and de- coration of a hall for a spring festival). Taste can, in natural beauty (the taste of fruit in an orchard) ; and so can temperature. Touch, perhaps ; but only exceptionally. Finally, reproduced sensations from the lower senses have three functions : as constitutive of the sensory aspect of the aesthetic object, as associatively connected with the visual or auditory presentation of the object, and as factors in the subjective experience induced by the object.] Literaturbericht. ZfilTSCHRIFT FUR PlIILOSOPHIE UND PHILOSOPHISCHE KRITIK. Bd. CXX., Heft 2. Jul. Bergmann. ' Ueber den Begriff der Quantitat' (Schluss).. [After defining in a former article all quantities whose magnitude can be numerically determined (both continuous and discrete) as ' numbers of things,' Bergmann subjects to a searching criticism a doctrine of Kant's which might be quoted against him. He then proceeds to consider in what sense his definition is applicable to certain categories of quantity where at first sight it seems inadmissible : intensity of quality, velocity and acceleration, probability, and the curvature of lines. All these are quantities since they admit of more or less ; but how can they be called numbers of things ? A line is made up of shorter lines, a surface of smaller surfaces, a weight of lesser weights, but red of a certain degree of saturation cannot be analysed into less saturated reds, nor a given velocity into slower speeds, etc. The solution is that the total amount is a sum of differences, of degrees measured from a zero-point which though counted as = may be in itself a very positive thing, as, for instance, the state of absolute rest from which degrees of velocity are counted is by no