378 Eelation of Watee to the Behavior op 



water, a condition with which our results on L. decemlineata agreed generally, 

 since the death-point in potato beetles with a high water-content was 58° to 

 60° C, and desiccated ones withstood 1° to °5 higher temperature. Bachmet- 

 jew (1903) shows that the temperature of the insect's body varied with the 

 conditions, namely, moisture, temperature, and the like. If the air was damp, 

 the body-temperature was higher than that of the surrounding medium, since no 

 evaporation occurred; but if the air was dry it cooled through evaporation. 

 He also pointed out that the smaller the percentage of fluids in a unit of the 

 liviag insect body, the lower was the normal congealing-point of the fluids. 

 Tower (1906) states that soil-temperatures taken on the savannas of Vera Cruz 

 in April 1904, in places where L. decemlineata was sestivating, were frequently 

 as high as 60° to 65° C, and that success in passing through these high tem- 

 peratures at the end of the dry season depended upon the completeness of the 

 physiological changes preceding entrance into hibernation. These results were 

 similar to those just given for this insect, which showed that the lower and 

 upper temperature limits were influenced through water-relation. 



In studying longevity in insects, Baumberger (1914) shows that the tem- 

 perature at which colloidal substances coagulate lowers with a decrease in 

 water-content and that long exposure to cold or high temperature may result 

 in this decrease in water. He explains that the result of a long exposure to cold 

 is the same as short exposure to heat, while intensity of cold shortens the length 

 of the period. He also demonstrates that the point of coagulation varies with 

 the water-content of the insects studied. Greely (1901) concludes that: 



" A reduction of the temperature and a loss of the water have similar effects, 

 because the cell loses water when the temperature is lowered, as well as when 

 the concentration of the surrounding medium is raised." 



The results of Livingston (1903) show for Spirogyra that a cell loses water 

 when the temperature is lowered. In discussing the reversal in animal instincts, 

 Loeb (1900) concludes that a decrease in temperature has the same physio- 

 logical effects as a loss of water. 



METABOLISM AND THE WATER-RELATION. 



The results of various workers show that desiccation modifies the rate of 

 metabolism; thus, the alterations in the behavior of the potato beetle may be 

 due to differences in metabolic activity, brought about through combined rela- 

 tions of water and temperature of the organism. Shelf ord (1913) states that 

 the changes in activity of the animals used in his experiments were due to the 

 withdrawal of water. 



It is known that anything which disturbs the rate of metabolism in an animal 

 alters its response to a stimulus, and that reversed reactions in behavior are 

 caused by changes in this metabolic process. According to Jennings (1904), 

 Child (1910), Wodsedalek (1911), AUee (1913), Phipps (1915), and others a 

 stimulus may change the physiological state of an animal, which produces a 

 modified type of reaction. Many depressing agents are also known, such as 

 potassium cyanide, chloretone, and a low oxygen content. Baumberger (1914) 

 shows that starvation is an agent of this character, since it decreases metabolism 

 by removing material to be oxidized. Loeb (1906), Mast (1911), Shelford 

 (1914), and others further demonstrate that acids and alkalis increase irri- 



