368 



Eblation op Watee to the Behavioe of 



The following conditions were experimentally planned in tube 1, containing 

 250 beetles, to give a low rate of evaporation, and the soil was kept moist by 

 adding water each morning and evening. This tube was kept filled with sprays 

 of Solanum hertwigii, which were kept fresh by having the stems in 350 e. c. 

 bottles filled with water, and the sprays were renewed twice daily ; it was also 

 necessary to wrap tinfoil about the top of the bottles to prevent the beetles from 

 drowning. The environmental conditions were apparently normal, for the 



water-condition, the food-supply, the low rate of evaporation, and the soil- 

 moisture were all favorable for the normal activities of the animals used (Table 

 10 for tube 1) in this problem. 



The following set of experimental conditions was maintained in tube 2, which 

 contained 350 beetles; however, in this case the soil was kept only slightly 

 moist and the first 5 cm. was used as a dry mulch, so that less moisture was lost 

 through evaporation. The same food plants, Solanum hertwigii, were added 



