240 CLAUDE FULLER. 



appear simple in structure. Ordinarily the compound nature 

 of a joint can be demonstrated ; at times the condition may 

 only be inferred. 



In the different castes of a given species there is a more 

 or less decided difference in the number of joints. It is 

 surprising that these differences have excited practically no 

 comment, nor have led to any serious effort being made to 

 explain them. They seem to have been regarded as inci- 

 dental to polymorphism, but an explanation cannot be offered 

 Avithout a comprehensive knowledge of the ontogeny of the 

 insect antenna. 



To me these termite organs are more than remarkable. 

 The degree to which they reflect the hereditary and environ- 

 mental action on the creature is a feature found in no other 

 appendage. During the course of growth they are subject to 

 the influence of inherited tendencies which are reacted upon 

 by the vicissitudes in the life of the individual. If the 

 organism is dwarfed by indifferent nutrition its antennae are 

 dwarfed and of fewer joints ; if the opposite condition 

 obtains the antennae may be composed of more joints than 

 usual. If the individual is arrested by other than nutritive 

 factors, so also are its antennte ; if it is subject to deviation, 

 as the production of a soldier, so also may the antennje be 

 modified more or less in accordance with the extent thereof. 

 With certain exceptions and details, not calling for recapitu- 

 lation here, the form of specialisation exhibited by termites is 

 one of reduction. The socially higher forms of termites have 

 been described as the most degenerate, but this is so only in 

 that sense in which man is also degenerate. It is curious to 

 reflect that the smaller the species the more it is specialised 

 among its congeners, and that the most specialised termites 

 are small ones. In short, all the evidence goes to show that 

 termites have been evolved from lai'ger insects and reduction- 

 of bulk has been one of the main lines of specialisation. The 

 principal evidence of specialisation by reduction is, however, 

 to be seen in the loss of a tarsal joint, in the loss of the 

 pulvillus, in the atrophy of the abdominal appendages, in the 



