10 STRUCTURE OF ANTS. 



least seven years old, and seem still quite strong and 

 well. I have also some workers which I have had in 

 my nests since 1875. 



The body of an ant consists of three parts : the 

 head, thorax, and abdomen. 



The head bears the principal organs of sense, and 

 contains the brain, as the anterior portion of the 

 nervous system may fairly be called. 



The thorax, supporting the legs, and when they are 

 present, the wings, contains the principal muscles of 

 locomotion. 



The abdomen contains the stomach and intestines, 

 the organs of reproduction, the sting, &c. 



Eeturning to the head : the antennae consist of a 

 short spherical basal piece, a long shaft, known as the 

 scape, and a flagellum of from six to seventeen (gene- 

 rallj'^, however, from ten to thirteen) short segments, 

 the apical ones sometimes forming a sort of club. The 

 number of segments is generally different in the males 

 and females. 



The eyes »re of two kinds. Large compound eyes, one 

 on each side of the head ; and ocelli, or so-called simple 

 eyes. The compound eyes consist of many facets. The 

 number differs greatly in different species, and in the 

 different sexes, the males generally having the greatest 

 number. Thus, in Formica pratensis there are, 

 according to Forel, in the males about 1,200 in each 

 eye, in the fertile females between 800 and 900, in the 

 workers about 600. Where the workers vary in size 



