THE GEOTROPISM OF PARAMECIUM CAUDATUM. 115 



eludes: "Es hat sich clahei herausgestellt, class durch Einwirkung 

 hoher Temperaturen . . . bei vielen Culturen vortibergehend 

 positiver Geotropismus hervorgerufen werden kann." And 

 "durch die Temperaturerniederingung (bis + 2) konnte ich 

 auch bei den sehr dazu geeigneten Aquarien keinen positiven 

 Geotropismus hervorufen." 1 On the contrary, Moore 2 states: 

 "Several tubes were left for three hours in a thermostat at a 

 temperature of 26-28 C. The Paramecia collected at the top 

 in dense clusters." And "tube B was placed in a larger tube 

 filled with water and surrounded by a mixture of ice and salt, the 

 temperature being kept as nearly as possible at i C. In ten 

 minutes the Paramecia in tube B were massed at the bottom, and 

 two hours later were still massed there." 



Sosnowski and Moore, however, gave no consideration to the 

 phenomena of the convection currents which would invariably 

 occur, when water was cooled or heated. That water currents 

 would produce effects on the geotropism of the animal was men- 

 tioned by the writer in his previous paper. The animals are 

 rheotropic. Moreover, the animals being so small cannot resist 

 any strong current. Consequently they would be passively 

 carried by the current, when it was strong. There was, there- 

 fore, needed a special device to minimize these effects as much as 

 possible. 



Dewar vacuum tubes served to some extent for this purpose. 

 The tubes were 3.2 cm. in diameter and 27 cm. long inside meas- 

 ure. Three tubes, one for control and the others for experiments, 

 cold and warm, were used for one series of experiments. It was 

 noted that warm water of 30 or 35 C., which was placed in one 

 of the tubes, with a rubber stopper, cooled off about 2 C. after 

 one hour, and water of i to 4 C. in the other became warmer 

 2 C. in about half an hour. Temperature of the control, that 

 was room temperature, was about 20 C. and fairly constant. 

 The dense culture of animals that were thoroughly washed was 

 cooled or warmed as desired. And a few drops of the culture so 



1 Sosnowski, J., 1899, " Untersuchungen iiber die Veranderungen der Geo- 

 tropismus bei Paramecium aurelia," Bull. Intern, d. I'Acad. d. Sci. d. Cracovie, 



S. 134- 



2 Moore, Anne, 1903, "Some Facts concerning the Geotropic Gathering of 

 Paramecium," Am. Jour. Physiol., Vol. 9, pp. 239 and 240. 



