Ants. 13 



provided with very large jaws. The large-headed 

 individuals are generally supposed to act as sol- 

 diers, and the size of the head enables the muscles 

 which move the jaws to be of unusual dimensions ; 

 but the little workers are also very pugnacious. 



2. Bates tells us that in the marching columns of 

 Eciton (a kind of South American ant) the large- 

 headed workers " all trotted along empty-handed 

 and outside the column, at pretty regular intervals 

 from each other, like subaltern officers in a march- 

 ing regiment ... I did not see them change their 

 position, or take any notice of their small-headed 

 comrades ;" and he says that if the column was 

 disturbed they appeared less pugnacious than the 

 others. 



In the Sauba Ant of South America there are 

 five distinct kinds of individuals. I have figured 

 two (fig. 5). They are sisters, and of the same age, 

 but so unlike one another that one would hardly 

 suppose they belonged to the same species. No 

 doubt they perform different duties. It has been 

 supposed that the large ones act as soldiers, but 

 the reason for the difference between the different 

 kinds of workers is still uncertain. 



3. For some little time after arriving at maturity, 

 ants devote themselves exclusively to the care of the 

 larvae and pupae, and take no share in the defence 

 of the nest or other out-of-door work until they 

 are some days old. This seems natural, because 

 lit first their skin is comparatively soft ; and it 



