1914.] NATURAL SCIENCES OF PHILADELPHIA. 297 



The manger, or feeding compartment, was 10 inches long, 8 inches 

 wide and 8 inches tall. It and the nest were not elevated above 

 the top of the table. The tops and bottoms of all four compart- 

 ments were glass, except the bottom of the run-way, which was 

 perforated tin. To make the bottoms of the nest and manger water- 

 tight an additional bottom made of plaster of Paris was added to 

 each of these compartments. The joints of the cage were so securely 

 covered with adhesive cloth and the tops fitted so snugly that 

 vapor collected on the tops and was transformed into large drops of 

 water. A large colony of Formica was found in a rotten log. A 

 half-bushel of the rotten wood and perhaps a quart of the ants with 

 brood of all stages were placed into the nest of the cage. 



A large flat piece of cotton wet with water w^as constantly kept 

 in each Fielde nest. A small piece of cotton was kept in each queen 

 cage, and a small amount of water was occasionally poured upon 

 the wood in the nest and twice a week water was put into the manger. 

 Honey, sugar syrup, queen-cage candy, live insects, and larvae of 

 various insects served as food. 



I. Experiments on Normal Ants and Hornets. 



To determine the relative sensitiveness of females, males, and 

 workers to various odors, under conditions which permitted of their 

 close observation, triangular experimental cases were used. These 

 were made of three narrow wooden strips, two of which were 5 and 

 the third 4 inches long, each strip being half an inch thick. Wire 

 screen served as a bottom and glass as a top for the case. The 

 apices and bases of these cases rested on two supports above a rigid 

 table and the table legs rested on a concrete floor, near a window. 

 Cheesecloth was spread across both supports, thus making a double 

 bottom for the cases. No screen was used to prevent the ants from 

 seeing the observer because they never showed any responses to the 

 movements made by the observer. 



The following sources of odor were used for determining the 

 reactions of the ants in the observation cases: Chemically pure 

 essential oils of peppermint, thyme, and wintergreen; food — honey 

 and comb, parts of plant leaves, and l)its of the stem of pennyroyal 

 (Hecloma pulegioides ?) ; ant secretion — ^formic acid. All these 

 substances except the last were kept in stoppered vials of the same 

 shape and size. The leaves and bits of the stem of the pennyroyal 

 were dried, but they still gave off a strong odor when the vial was 

 uncorked. The formic acid was obtained by squeezing the abdomen 



