DWELLINGS. 219 



without. Gradually the storey reaches a sufficient 

 height. It remains to cover it, and this is not the 

 easiest part of the business. The ceiling is formed 

 of vaults going from one wall to another, or from, a 

 wall to a column. When one of these vaults is to be 

 small, some millimetres at the most, the Formica fusca 

 constructs it with the help of two ledges, which are 

 made facing each other on the tops of two partitions. 

 These prominences, formed of materials glued to- 

 gether by saliva, are enlarged by additions to their 

 free edges. They advance to meet each other and 

 soon join; it is wonderful to see each insect, follow- 

 ing its individual initiative, profit by every twig or 

 fragment capable of bearing any weight, in order to 

 enlarge the overhanging ledges. 



Individual skill and reflection. — This personality in 

 work, which reveals the intelligent effort of each, has 

 certainly its inconveniences for the common work. 

 Badly-concerted operations may not succeed, and 

 Huber witnessed an accident due to this cause.^ Two 

 walls facing each other were to be united by an arch. 

 A foolish worker had begun to form a horizontal 

 ledge on the summit of one of the walls without 

 paying attention to the fact that the other wall was 

 very much higher. By continuing the project the 

 ceiling would have come against the middle of the 

 opposite ceiling instead of resting on its summit. 

 Another ant passes, examines affairs with an intel- 

 ligent air, and evidently considers that this sort of 

 work is absurd. Without consideration for the 

 amour-propre of its unskilful fellow-citizen, it de- 

 molishes its work, raises the wall that is too low, and 

 re-makes the construction correctly in the presence 

 ^ Recherches sur les Mceurs des Fourmis indigines, pp. 47, 48. 



