REACTIONS OF CERTAIN MOIST FOREST MAMMALS. 195 



forest. The rate of evaporation is much greater on the prairie 

 due to a more direct effect of the wind and a higher temperature. 



In Experiment 13, Chart I., the rates of flow were 20, 35.5 and 

 50 liters per minute respectively; the filters and moisteners were 

 both cut out of the air supply leading to the experimental cages. 

 While most of the time was spent in the division representing the 

 lowest evaporation the mouse never behaved normally; the 

 lowest evaporation appearing to be above the optimum, and no 

 doubt it was much greater than that encountered in the natural 

 environment. In Experiment 12, Chart I., the rates of flow were 

 30, 30, and 40 liters per minute. The filters were cut out in this 

 experiment while the moistener were left in, which accounts for 

 the variation between the two 3O-liter flows. The mouse showed 

 a marked avoidance to the more rapid rate of flow. At the end 

 of fourteen minutes the mouse was asleep in the division of lowest 

 evaporation and remained there throughout the experiment. At 

 the end of this experiment the ends were reversed. The mouse 

 up to this time had been asleep but was now stimulated and 

 after the first few minutes grew very restless, turning around in 

 the corner and showing various other stimulation reactions similar 

 to those described under the dry-air experiments. The mouse 

 after ten minutes had elapsed moved to the end of lowest evapor- 

 ation which it had previously selected and remained there 

 throughout the experiment except at the end of the 2yth minute, 

 when it was forced out by the experimenter. 



Only a general idea of the effect of raising the temperature 

 can be obtained as the apparatus for this part of the experiments 

 was faulty. It was impossible to keep the temperature constant, 

 and the atmometers and the water in the burettes should have 

 been at the same temperature as the air used, if the results are 

 to be comparable with those obtained at room temperature. 

 Even though the data may not be accurate the number of ex- 

 periments performed give a fair indication of the general effect 

 upon the organism as is indicated by the general behavior of 

 the mice in all the experiments. 



The various temperature gradients were obtained by passing 

 the air through coils of aluminum tubes exposed to steam. In 

 some cases the pressure exerted on the air in these coils was suf- 



