240 INSTINCT. Chap. VII. 



smaller workers, with some of intermediate size ; and, 

 in this species, as Mr. F. Smith has observed, the 

 larger workers have simple eyes (ocelli), which though 

 small can be plainly distinguished, whereas the smaller 

 workers have their ocelli rudimentary. Having care- 

 fully dissected several specimens of these workers, I 

 can affirm that the eyes are far more rudimentary in 

 the smaller workers than can be accounted for merely 

 by their proportionally lesser size ; and I fully believe, 

 though I dare not assert so positively, that the workers 

 of intermediate size have their ocelli in an exactly inter- 

 mediate condition. So that we here have two bodies 

 of sterile workers in the same nest, differing not only in 

 size, but in their organs of vision, yet connected by some 

 few members in an intermediate condition. I may 

 digress by adding, that if the smaller workers had been 

 the most useful to the community, and those males and 

 females had been continually selected, winch produced 

 more and more of the smaller workers, until all the 

 workers had come to be in this condition ; we should 

 then have had a species of ant with neuters very 

 nearly in the same condition with those of Myrmica. 

 For the workers of Myrmica have not even rudiments 

 of ocelli, though the male and female ants of this genus 

 have well-developed ocelli. 



I may give one other case : so confidently did I 

 expect to find gradations in important points of structure 

 between the different castes of neuters in the same spe- 

 cies, that I gladly availed myself of Mr. F. Smith's offer 

 of numerous specimens from the same nest of the driver 

 ant (Anomma) of West Africa. The reader will per- 

 haps best appreciate the amount of difference in these 

 workers, by my giving not the actual measurements, 

 but a strictly accurate illustration: the difference was 

 the same as if we were to see a set of workmen building 



