- 



ANTS. 



a further extension and modification of the cocoon-spinning activities. 

 In this case the -pinning powers of the larva are utilized for the pur- 

 pose of producing an envelope, not for its individual self, hut for the 

 whole colony. In conventional works this latter activity would he 

 assigned a prominent place as a typical instinct, the spinning of the 

 cocoon might also he included under this head, but the formation of 

 the puparinin. or pupal skin, would be excluded as a purely physiolog- 

 ical or developmental process, yet this last, no less than the two other 

 cases, has all the fundamental characteristics of an instinct. 



Viewed in this light there is nothing surprising about the complexity 

 and relative -fixity of an instinct, for it is inseparably correlated with 

 the structural organization, and in this we have long been familiar both 

 with the dependence of the complexity and fixity of parts on heredity 

 and the modifiability of these parts during the life-cycle of the indi- 

 vidual. Fixed or instinctive behavior has its counterpart in inherited 

 morphological structure as does modifiable, or plastic, behavior in well- 

 known ontogenetic and functional changes. 



There is no better group for the study of instinct, both as a stereo- 

 typed heredity activity and in its correlation with structure, than the 

 ants. Wundt and others have called attention to the fact that all instincts 

 center about alimentation and reproduction, and that in these processes 

 themselves we have the most typical instincts. As alimentation may 

 be regarded as subservient to reproduction, we may say that all instincts 

 converge towards the propagation of the species. This statement meets 

 with no exception in the ants on account of their social organization. 

 On the contrary, this merely lends it greater emphasis. All the for- 

 aging, nest-building and other activities revolve about the care and 

 education of the brood, and, as has been shown in Chapters XIX, XXI 

 and XXII, even the extravagant and aberrant activities that these 

 insects exhibit in their tolerance and care of myrmecophiles and para- 

 sites, have their origin in the same obsessional generative instincts. 



The ant colony, as many authors have suggested, is analogous to 

 a single large organism, in which the soma is represented by the body 

 of workers, the reproductive organ by the fertilized queen. It follows, 

 of course, from this conception that the differentiation of the colonial 

 soma into castes is merely the visible result of a psychological and 

 physiological division of labor. It is also noticeable that in the ant 

 colony the closer instincts come to those of pure growth, development 

 and reproduction, the more fixed and mechanical they appear, whereas 

 the ancillary and more remote ethological instincts, like those of for- 

 aging and nest building and those relating to other organisms such as 

 alien ants, myrmecophiles and parasites, are much less constant and 



