CLYDE C. HAMILTON. 



dition at the end of the experiment than either of the larvae used 

 in graphs 9 and 10. 



In testing the resistance of larvae to evaporation, in the glass 

 tubes previously mentioned, one larva died at the end of 115 

 minutes' exposure in the tube containing the dry air at a tem- 

 perature of 22.5 C. and a relative humidity of 9 per cent. The 

 larvae in the tubes containing the medium air, relative humidity 

 64 per cent, and temperature 22.5 C., and the wet air, relative 

 humidity 95 per cent, and temperature 22.5 C., were not 

 affected at the end of two hours. At a temperature of 23 to 

 24 C. another larva lived 75 minutes in the tube containing air 

 with a relative humidity of 4 per cent., another one 120 minutes 

 in the tube containing medium air with a relative humidity of 

 40 per cent., while in the tube containing the wet air, relative 

 humidity about 80 per cent., the larva was slightly shrunken and 

 inactive at the end of 160 minutes but not dead. The tempera- 

 ture had risen to about 26 C. when the experiment was discon- 

 tinued. In testing the resistance of larvae to gradients of 

 evaporation, produced by different rates of air flow, at a temper- 

 ature of 21.5 C. and a relative humidity of 7 per cent., one larva 

 died after 35 minutes' exposure with an air flow of 16.4 liters per 

 minute or 4.5 millimeters of water displaced. During this time 

 2.1 c.c. of water had evaporated from the porous cup atmometer. 

 In air of the same temperature and relative humidity but an air 

 flow of 13.3 liters per minute or 3 millimeters of water displaced, 

 another larva died at the end of 68 minutes, with an evaporation 

 of 3.2 c.c. of water from the porous cup atmometer. With an 

 air flow of 9.3 liters per minute or 1.5 millimeters of water dis- 

 placed a third larva died after 90 minutes' exposure with an 

 evaporation for this period of 3.4 c.c. of water from the atmom- 

 eter cup. The air was the same temperature and relative 

 humidity as in the previous two experiments. The larva in the 

 tube containing the larger flow of air was considerably disturbed 

 from the first and rolled and twisted about. The larvae in the 

 other two tubes did not behave so violently but gradually became 

 sluggish and less active until they died. 



C. Reactions in Carbon Dioxide Gradients. Graphs 12, 13 and 

 14 show the reaction of larvae to air containing different percen- 



