American journal of physiology . effect as lowering thetemperature. It is well known that raising the concentration of thesalt solution causes the organism or tissue to give off water, but whya reduction of the temperature has an analogous effect has neverbeen explained. It is hoped that the present experiments will throwsome light upon this problem. At first the effect of changing the temperature was tried onthe common blue-green Stentor coeruleus. The Stentor were keptin small covered dishes, and the water was renewed each day fromthe aquarium in which the Stentor had been grown. This con-ta
American journal of physiology . effect as lowering thetemperature. It is well known that raising the concentration of thesalt solution causes the organism or tissue to give off water, but whya reduction of the temperature has an analogous effect has neverbeen explained. It is hoped that the present experiments will throwsome light upon this problem. At first the effect of changing the temperature was tried onthe common blue-green Stentor coeruleus. The Stentor were keptin small covered dishes, and the water was renewed each day fromthe aquarium in which the Stentor had been grown. This con-tained an abundance of food material. The animals were dividedinto three lots: — Lot I was kept at the room temperature (20° C.) as control material. Lot 2 was surrounded by a mixture of ice and salt. Lot 3 was placed in a thermostat at a temperature of from 25° to 28° C. ^ LoEB : Physiology of the brain, 1900, p. LoEB: Journal of morphology, 1892, vii, p. 253. ^ Ibid. 122 Loss of Watei and Lowering of Temperature. 12,. When the temperature was suddenly lowered to the freezing point,and ice was allowed to form in the dish containing the Stentor, theanimals immediately became quiet. Death took place when thefreezing point was reached. The cell outlines became extremelyirregular and shrunken, and the blue-green pig-ment, stentorin, was rapidly diffused through thewater. These irregular cells remained intact fora short time, but soon disintegrated. A very different result was obtained when thetemperature was lowered gradually. The dishcontaining the Stentor was at first loosely sur-rounded with ice, so that the temperature sank toabout lo^ C. More ice and salt were then added,and the temperature allowed to fall for an hour,until zero was reached, or until a film of ice beganto form around the edges of the dish. Under these conditions the Stentor soon became quiet, except for a lively contraction of the buccal and peristomal cilia, and remained so for from one to three hou
Size: 1108px × 2255px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookautho, bookcentury1800, bookdecade1890, booksubjectphysiology
