THE ANATOMY OF BUTTERFLIES 



The body of a butterfly consists of the head, the thorax, and the abdomen 

 (see Plate A, Fig. c). 



The head carries two relatively large eyes, one on either side. The eyes of 

 insects are compound, and if examined under a microscope are seen to have a mul- 

 titude of minute facets, which serve to gather the light from all directions, so that 

 butterflies can look forward and backward, upward and downward, as well as out- 

 ward, all at one time. Between the eyes on the upper part of the head arise the 

 antennae, of which we have already spoken. The precise function of these organs 

 in insects has been the subject of much discussion. Supposed by some to be ears, by 

 others to be the seat of the sense of smell, by others to combine within themselves 

 these two senses, and by still others to represent a sense which is not possessed 

 by vertebrate animals, their use in the life of insects is not yet clearly under- 

 stood. The weight of evidence seems to be in favor of the view that they are or- 

 gans of smell, and it is now quite firmly established by experiment that the organs 

 of hearing in insects are represented by certain pores and openings on their legs. 

 In front between the eyes and below the antennae are two little organs, each com- 

 posed of three joints, which are known as the labial palpi (see Plate A, Fig. e). 

 Between these, coiled up like a watch-spring, is the proboscis, with which the but- 



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