BUCKINGHAM. — DIVISION OF LABOR AMONG ANTS, 429 



and structure intermediate between these two, while in function it 

 sometimes resembles the large and sometimes the small. 



Often the same occupation is seen to belong to one class in one 

 species and to another in another species. 



That in general the greater amount of work is done by a few workers 

 is the contention of Miss Fielde (:03d, p. 621) and of Forel ('74, p. 151). 

 Lubbock ('82), working on foraging in Formica fusca, came to the same 

 conclusion, but made no study of the relation of activities to size. 

 Pricer thinks that in Camponotus it is the medium-sized ants which 

 accomplish most, whereas Forel believes that the small ones do the 

 most work. But I know of no case where in a given species a large 

 number of functions have been studied in relation to class distinctions. 



Therefore without further evidence we are not in a position to state 

 definitely the relation of size and form to division of labor. 



III. Polymorphism of Ants. 

 A. Polymorphism in General. 



In order to study satisfactorily the correlation between polymorphism 

 and division of labor, it is necessary to define what is meant by poly- 

 morphism. Wheeler (:10, p.. 86) says that only those animals properly 

 represent the phenomena of polymorphism " in which characteristic 

 intraspecific and intrasexual groups of individuals may be recognized, 

 or, in simpler language, those species in which one or both of the sexes 

 appear under two or more distinct forms." 



According to "Wheeler (see also "Wheeler, :07^ p. 85) and to Esche- 

 rich (:06, p. 45) polymorphism is commonly supposed to be due to a 

 physiological division of labor. 



Though both sexes of ants show some tendency to polymorphism, 

 such as is described for males by Wheeler {'-Q^^), by Forel (:04* ; =04'^), 

 and by Emery ('86 ; :06), polymorphism is not common in the male 

 sex, and we are not here concerned with that manifestation of it. If, 

 however, we confine our attention to the females of a colony of ants, it 

 will be found that they are, as a rule, markedly polymorphic, consisting 

 of two chief divisions, queens and workers ; although in some cases 

 (certain Ponerinae) there are no apparent distinctions between the 

 queen and the worker classes, the two forms being connected by indi- 

 viduals of an intermediate character (Wheeler, :00% p. 1 ; :10, pp. 242- 

 243). Wheeler (: 00=*) feels certain "that forms externally indistin- 

 guishable from the workers commonly function as females." Again, 

 he (:03'', p. 6) says of Leptothorax emersoni that many workers ap- 

 proach the queens in size, possess ocelli, and probably function as 



