32 THE ARGENTINE ANT. 



METHODS OF STUDY. 



WTicn the study of this ant was undertaken, two requisites presented 

 themselves — a type of artificial formicary in which continuous obser- 

 vations could be made and individuals kept track of from the time of 

 egg deposition until the adult stage was reached, and some method 

 by which all individuals of a colony could be confined to their own 

 formicary. 



Space need not be taken to describe the types of artificial formicaries 

 which were not successful. 



The Janet cages proved successful only in the case of very large 

 colonies, but in these the multipUcity of individuals made accurate 

 observations impossible. It may be remarked that this type of cage 

 is excellent for studying the comnmnity life as a whole and for making 

 expermients ^vith poisons or mth parasitic fungi or bacteria. 



Cages totally inclosed were not successful, for the reason that the 

 ants, when deprived of the privilege of leaving their nest, failed to act 

 in a normal manner. 



The cage finally adopted was, wdth modifications, the one described 

 by Su' John Lubbock on pages 2 and 3 of his classic work.^ This 

 consists essentially of two glass plates containing between them a 

 layer of pulverized earth in which the ants may burrow at their 

 pleasure. Considerable difficulty was experienced in getting the 

 glass plates the proper distance apart; if too far apart the ants could 

 make burrows which were not open to observation, and if too close 

 together insufficient room was afforded the queen in which to stand 

 and walk upright. As the queen is about twice as tall as the worker, 

 it seemed for a time that a suitable cage could not be constructed. 

 After repeated trials, however, it was found that if the space between 

 the glass plates were made exactly 1.75 mm. the queen would have 

 sufficient room and the workers could not construct invisible galleries. 



This type of cage and its supporting stand are well illustrated by 

 figures 7 and 8. Figure 7 shows the several parts of the cage; 3 is the 

 cage proper, consisting of two plates of glass held uniformly 1.75 

 millimeters apart by strips of leather at all four edges, a door or open- 

 ing being left at one corner. (See fig. 9.) Old negatives, the films 

 removed with caustic soda, have been found the most desirable for 

 making these cages, both because such glass is remarkably clear and 

 free from imperfections and because it is of uniform thickness. The 

 size of the cage may vary from 3^ by 4J up to 8 by 10 inches or even 

 larger. Leather was found more satisfactory for maldng the edges 

 of the cage than either glass or wood. The strip of leather between 

 the glass margins is about ^ inch in width. It is extremely difficult 

 to find a strip of glass uniformly 1.75 millimeters thick and it is also 



' Avcbury. Ants, bees, and wasps, 1881. 



