. Contributions to the study of the behavior of lower organisms. Physiology, Comparative; Infusoria; Amoeba; Irritability. REACTIONS TO IN CILIATES AND FLAGELLATES. half of the circular area, making a sharp line {x-y, Fig. 11) dividing the light from the darkness. A mirror was placed above the microscope, inclined in such a position as to project the image of the Stentors, very much magnified, on the ordinary vertical screen used for receiving lantern slide views. Thus the behavior of the Stentors could be studied with great ease on the screen. The heat from the lantern was cut out, so
. Contributions to the study of the behavior of lower organisms. Physiology, Comparative; Infusoria; Amoeba; Irritability. REACTIONS TO IN CILIATES AND FLAGELLATES. half of the circular area, making a sharp line {x-y, Fig. 11) dividing the light from the darkness. A mirror was placed above the microscope, inclined in such a position as to project the image of the Stentors, very much magnified, on the ordinary vertical screen used for receiving lantern slide views. Thus the behavior of the Stentors could be studied with great ease on the screen. The heat from the lantern was cut out, so far as possible, by placing between it and the mirror of the microscope a glass cell three inches thick, filled with cold water. In this manner the heat was excluded to such an extent as to fall below the threshold for the stimulation of Stentor by heat. This was demonstrated by comparing the reactions of Stentor with those of Paramecium. Stentor is less sensitive to changes in temperature than is Paramecium ; this was clear in my ex- periments on the reaction to heat. Par- amecium does not react at all on passing into the area illuminated by the lantern, but swims about indiflerentlv in both the dark and the light parts of the dish, show- ing that the heat produced is below the threshold for Paramecium ; it must then be below the threshold for Stentor. The free Stentors in the unlighted part of the vessel swim about at random. Many individuals thus come by chance to the line x-y. Fig. ii, where they would pass into the lighted area. These at once back a little, then turn toward the right aboral side, and swim forward again. The turning toward the right aboral side is usually through an angle sutKcient to direct the Stentor away from the lighted area (see I, 2, 3, 4, Fig. 11) ; if it is not, tlie Stentor repeats the reaction until, after one or two trials, it swims into the unlighted region. Many of the individuals react as soon as the anterior end reaches the lighted area, so
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiol, bookyear1904
