14 CHARLES F. W. McCLURE 



havior is illustrated by experiment 442 A (fig. 3), in which 

 the initial loss in weight of the glove amounted to 25 per cent 

 during the first hour of its suspension in Ringer ; then a gain 

 in weight followed up to the twenty-sixth hour, when the 

 weight remained stationary until the molt skin was removed 

 from the glove. The behavior of the glove in experiment 

 461 A (fig. 3) differs slightly from that observed in the last- 

 mentioned experiment. In experiment 461 A a very slight 

 gain in the weight of the glove, during the first hour of its 

 suspension in Einger, was succeeded by a loss which con- 

 tinued for five hours, after which there was a slight gain. 

 The two frogs from which these skins were taken were very 

 thin and weak, and, in experiment 461 A, the frog used was 

 quite emaciated. 



In figure 4 is graphically shown another experiment (437) 

 made on a skin glove removed from the hind leg of a frog 

 (R. pipiens) which was thin and which had molted just prior 

 to the removal of the skin from the body. This experiment 

 is interesting as showing the influence of temperature on the 

 weight of a glove with the outside of the skin turned outward, 

 filled with Ringer's solution approximately isotonic with 

 frog's blood and alternately suspended in the same solution 

 'at different temperatures. During the first five hours of its 

 suspension in Ringer at 17C., the glove either gained or 

 remained stationary in weight ; when transferred to the same 

 solution at 27 C., however, the glove lost. Between the fifth 

 and twentieth hours, the gain in weight of the glove was con- 

 tinuous, irrespective of differences in temperature ; after this, 

 however, in relation to temperature changes, the weight 

 showed fluctuations similar to those of the first five hours. 

 While this type of behavior does not appear to be especially 

 common, a sufficiently large number of cases has been ob- 

 served to justify placing it among the typical forms which 

 one occasionally encounters. Perhaps the most important 

 and significant feature of this last-mentioned behavior is that 

 exactly similar fluctuations in body weight can be produced 

 in the living frog when the latter is transferred from water 

 at one temperature to water at another. 



