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These experiments are in continuation of investigations on the perception of passive motion — more especially rotary motion — in which the reacters were vertebrates having semicircular canals. In this case invertebrates — snails, flies, beetles, ants, caterpillars, and ear-wigs — were placed on the rotary table and their reactions to rotary motion observed. S. found that the 'reacters' moved on a plane table against the motion of the table, though not in every case. The caterpillars did not move at all, the snails not always, and the beetles, ants, flies, and ear-wigs only when they were already in motion. Unlike the vertebrates, the invertebrates investigated showed no after effects of the rotary motion in the form of rotary giddiness.

The earliest investigators had found that the eye was most sensitive to change of color near the D line of the spectrum (yellow). Next to this came the region near the F line (blue). Later, König and Dieterici found the maximum sensitiveness just left of the F line. Using an apparatus in which the adjacent spectra compared were produced by an equilateral flint-glass prism, the author compares his green-blind eye with A. König's normal eye. The method of mean errors was used, and for each region of the spectrum investigated fifty adjustments were made. B. found first that the greatest sensitiveness to difference for his green-blind eye was slightly to the left of the maximum for normal eyes, i.e. to the left of F; left from the maximum, the green-blind eye shows more sensitiveness than the normal, but then decreases rapidly, while the normal eye shows a second maximum in the yellow. Surmising that another small increase in the curve of sensitiveness beyond the F line was due to change in intensity rather than quality of light, B. varied the brightness of the fields of color. For both the normal and the green-blind eye the slight increase beyond F disappeared, while throughout the observed range of colors the sensitiveness became somewhat less. Similar results were found by W. Uthoff (Gräfes Archiv, 1888, Bd. 34), who used the method of minimal changes.

The investigation of Maudi, the French 'lightning calculator,' seems to show that he is more remarkable for memory than for the rapidity or