394 EVOLUTION AND ANIMAL LIFE 



make slaves of the conquered ants. There are numerous 

 species of the so-called slave-making ants. The slave-makers 

 carry into their own nest the eggs and larvae and pupae of the 

 conquered community, and when these come to maturity they 

 act as slaves of the victors that is, they collect food, build 

 additions to the nests, and care for the young of the slave- 

 makers. This specialization goes so far in the case of some 

 kinds of ants, like the robber-ant of South America (Eciton), 

 that all of the Eciton workers have become soldiers, which no 

 longer do any work for themselves. The whole community 

 lives, therefore, wholly by pillage or by making slaves of other 

 kinds of ants. There are four kinds of individuals in a robber- 

 ant community winged males, winged females, and small and 

 large wingless soldiers. There are many more of the small 

 soldiers than of the large, and some naturalists believe that the 

 few latter, which are distinguished by heads and jaws of great 

 size, act as officers! On the march the small soldiers are ar- 

 ranged in a long, narrow column, while the large soldiers are 

 scattered along on either side of the column and appear to act 

 as sentinels and directors of the army. The observations made 

 by the European students of ants, Huber, Forel, Emery and 

 Wasmann, and by McCook and Wheeler in America, read like 

 fairy tales, and yet are the well-attested actual phenomena of 

 the extremely specialized communal and social life of these 

 animals. 



The bumblebees and social wasps show an intermediate 

 condition between the simply gregarious or neighborly mining 

 bees and the highly developed, permanent honeybee and ant 

 communities. Naturalists believe that the highly organized 

 communal life of the honeybees and the ants is a develop- 

 ment from some simple condition like that of the bumblebees 

 and social wasps, which in its turn has grown out of a still 

 simpler, more gregarious assembly of the individuals of one 

 species. It is not difficult to see how such a development could 

 in the course of a long time take place. 



The termites or white ants (not true ants) are also communal 

 insects. Some species of termites in Africa live in great mounds 

 of earth, often fifteen feet high. The community comprises 

 hundreds of thousands of individuals, which are of as many as 

 eight kinds or castes (Fig. 247) viz., sexually active winged males, 

 sexually active winged females, other fertile males and females 



