December, '17] crumb and lyon: house-fly and chemicals 



Table 2. — Comparison op the Results Obtaixed with Carbon Dioxide and Ammonia 



535 



The two sets of units in the above experiments were placed from 4 

 to 6 inches apart in a series and air was bubbled through the ammonia 

 at rates varying in different units from 12 to 240 bubbles per minute. 

 The lower rate gave the bran only a faint ammoniacal odor at the end 

 of the experiment while the higher gave the bran a powerful odor of 

 the gas. The ammonia used was of U. S. P. strength diluted with an 

 equal volume of water, and one hundred cubic centimeters of the Hquid 

 were placed in each bottle. The experiments were run the greater 

 part of the time with five ammonia units and three carbon dioxide 

 units equably distributed, thus giving the ammonia the greater oppor- 

 tunity for profiting by chance oviposition. It will be noted that the 

 carbon dioxide received 91.4 per cent of the unit average of the eggs 

 deposited while the ammonia received 8.6 per cent. This ratio is 

 very nearly the same as that shown in Table 1, in which carbon dioxide 

 and air are compared. 



Table 3. — Comparison op the Results Obtained with Ammonia and Am 



Eight units divided equallj' between the ammonia and air were run 

 throughout these experiments. The ammonia was of the strength 

 and quantity used in the previous series and an equal amount of water 

 was placed in the check bottles. The two sets were placed alternately 

 about one foot apart and three of the adjacent pairs of bottles, one 

 containing ammonia and the other water, had air bubbled through the 

 liquid at equal rates, varying in different pairs from 5 bubbles to 250 

 bubbles per minute, the usual series being about 12, 24, and 180 

 bubbles per minute respectively. An additional check bottle had no 

 air current and the remaining ammonia had air bubbled through the 

 liquid at some rate intermediate with the above. No oviposition 



