DEVELOPMENT OF THE ANTENN.T^ OP TERMITES. 237 



5. In all species and castes examined, joint III of the 

 antenna in its final form exists as a cajDsnle enclosing a 

 series of joint-elements, and, thei'efore, all such antennae are 

 to be regarded as essentially arrested organs, even in the adults. 



6. On hatching from the egg the development of the 

 antenna generally reaches an external phase of X or XII 

 joints, according to the species. 



7. The final number of joints is due to the abjunction of 

 many or few new joints in an acrogenous manner from 

 joint III. 



8. 'i'he process of joint-multiplication ceases during or 

 before the fourth instar. 



9. The mode of increase in the number of the joints is the 

 same in all species except in Hodotermes. Typically two 

 joints are abjuncted from joint III periodically, so that all 

 new joints are arranged in pairs — i. e. as sister-joints. 



10. All odd-jointed antenna developing by the common 

 mode originate either from the fusion of sister-joints when in 

 the elemental stage before abjunction, or by the non-abjunc- 

 tion from III of the more proximal of such a pair. 



11. The length of joint III in the final organ is dependent 

 upon the stage of development of the joint-elements and the 

 number of these contained within it when the process of 

 multiplication ceases. 



12. The soldiers and workers of a termite community have 

 a curtailed development and pass through fewer stadia of 

 growth than do their corresponding imagos. 



13. In the evolution of termites a new factor arose — the 

 building up of a food reserve — and the comparatively early 

 subsidence of joint multiplication in the antennas of the imagos 

 probably had its first cause in this. 



14. The tendency of termites to specialise into various 

 castes by the differentiation and reduction of parts or of the 

 whole body also influences the post-embryonic development 

 of the antenna, in that — 



(1) Soldiers tend to have fewer joints than their 

 corresponding workers. 



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