1921] The Age of Insects 29 



through matter," as the common source from which sprang in different 

 directions both instinct and intelligence. This view leads us away 

 from the commonly accepted theory that consciousness must be con- 

 sidered as that inmost luminary which enlightens our actions. It is 

 possible, even probable, that this kind of consciousness exists to a 

 greater or lesser extent in the animals. However, we can not know 

 anything about it, and we believe with Ed. Claparede that "the science 

 of animal psychology may and must scrutinize the problem of the 

 greater or less intelligence of animals without being concerned about 

 their consciousness." 



We discern intelligence in its simplest expression wherever we 

 notice a choice between the various alternatives offered by circum- 

 stances, and in one of its highest forms wherever we observe that pow- 

 er of invention which, according to Bergson, enables the human race 

 to "manufacture artificial objects, more particularly to make tools 

 with which to make other tools and to vary their fabrication indefi- 

 nitely. " These two extreme forms are naturally connected by a 

 series of links, and we know that the one as well as the other plays a 

 part in the behavior of arthropods. The latter of the two seems, how- 

 ever, to be rather exceptional in our group, showing itself only in the 

 primitive state consisting of the use of foreign bodies as implements. 

 The tool used by Ammophila is a small stone with which the female rams 

 and packs the dirt that closes her burrow. With certain ants of 

 India {Oecophylla sinaragdina) and of Brazil {C am/ponotus texter) the 

 instrument consists of the larva of the species itself. Held between 

 the mandibles of the workers, these larvae, by means of their thread, 

 glue and fasten edge to edge the leaves of which the nest is constructed. 

 The implement of the crabs, of the genus Melia, in the Indo-Pacific 

 seas, is supplied by a delicate sea-anemone. This is held between the 

 pincers of the animal, which probably uses the nettling exudations to 

 paralyze its prey. 



Facts of this nature are rare in the world of arthropods, but they 

 have an important significance. The use of the little stone is not yet 

 a fixed habit wdth Ammophila, it belongs only to certain individuals 

 more highly endowed than others and is perhaps only accidental even 

 with them. Maybe it will finally pass into the instinctive habits of 

 the species; for the present it belongs to the domain of individual in- 

 telligent acts. The crabs of the genus Melia are already farther ad- 

 vanced, all the species carry anemones and all exhibit a curious modi- 

 fication of the pincers, the fine teeth having become elongated and 



