ANTS NESTS. 



347 



like the one that received light normally. The others exhibited a 

 varying quantity of pigmentary cells and chromatophores. Under 

 these conditions, it really seems as if the absence of pigment in 

 the animals in normal conditions is due to the difference of circum- 

 stances, and that light is the agent that determines the develop- 

 ment of the pigmentary cells. It cannot be the only one, 

 however, for pigments exist in many animals dwelling in the 

 darkness of great depths. 



ante' ncQtQ* 



By Dr. August Forel. Plates XIX. and XX. 



A NEST is a temporary or permanent, naturally or artificially 

 formed hiding place, which serves as a dwelling for an 

 animal and its family or for a more numerous society of 

 animals. The nest is also intended, at the same time, for protec- 

 tion against enemies and against the inclemency of the weather 

 and of the temperature. There are, however, not only purely 

 natural nests (such as natural caves and hollows) and purely arti- 

 ficial nests (such as blackbirds' nests), but also, in many cases, 

 mingled forms, where natural hiding places are completed by 

 artificial help. Nests may also be divided into transient or season 

 nests and permanent nests. 



Now, in the case of animals which live in large societies — such 

 as beavers, wasps, and ants — the nest becomes a complicated 

 building or labyrinth. There are also elaborate and rough primi- 

 tive nests. 



The ants, or Formicidae, form a great family of the insect 

 order of the Hymenoptera. They number upwards of two thou, 

 sand known species, which form about one hundred and fifty 

 genera, distributed throughout the whole earth. All species of ants 

 live in societies, and almost all display a peculiar so-called polymor- 

 phism ; that is, every species consists, not only of a female, usually 



* Translation of Die Nester der Ameisen. Von Dr. August Forel, Profes- 

 sor in Zurich. Neujahrsblatt der Naturforschendeti Gesellschaft zu Zurich, 

 1893. From Smithsonian Report, 1894. 



