58 INTRODUCTION. 



which forms a canal through whicli the alimentary 

 juices are absorhed. This instrument, which is some- 

 times of great length, is spirally convoluted when 

 unemployed, but it can be unrolled with great ra- 

 pidity, and is admirably fitted to explore the tubular 

 corollas and deep-seated nectaries of flowers, for the 

 purpose of extracting their sweet secretions. It is 

 of a cartilaginous substance, and owes its great flexi- 

 bility to its being composed of numerous rings or 

 transverse fibres, bearing some resemblance to the 

 annulose structure of earth-worms and some other 

 animals. It is formed of two distinct pieces, which 

 admit of being separated throughout their whole 

 length. Each of these pieces is traversed longitu- 

 dinally by a cylindrical tube, and being grooved on 

 their inner side, they form when united another ca- 

 nal in the centre, of a somewhat square form, and 

 wider than either of the two lateral ones. The junc- 

 tion of the two parts is so close that the enclosed tube 

 is perfectly air-tight ; and this union is effected by 

 means of an infinite number of filets, resembling 

 the laminae of a feather, which interlace and adhere 

 to each other. Of these three tubes, the central 

 one alone serves for the influx of the alimentary 

 fluids, the two lateral ones being probably employed 

 in transmitting air in aid of respiration, which, how- 

 ever, is mainly carried on by means of stigmata or 

 lateral pores. The outer extremity of the proboscis 

 is frequently beset with many membranous papillae, 

 resembling leaflets, which have been regarded by 



