METHOD OF USE 81 



those with which they are connected in the 

 head and body ; and at the moment of ap- 

 plying its proboscis to the food it makes an 

 inspiratory effort, by which the central canal 

 in the proboscis is dilated, and the food as- 

 cends it at the same instant to supply the 

 vacuum produced; and thus it passes into the 

 mouth and stomach ; the constant ascent of 

 the fluid being assisted by the action of the 

 muscles of the proboscis, which continues dur- 

 ing the whole time that the insect is feeding. 

 By this combined agency of the acts of 

 respiration and the muscles of the proboscis 

 we are enabled to understand the manner in 

 which the humming-bird sphynx extracts in 

 an instant the honey from a flower while 

 hovering over it, without alighting, and which 

 it certainly would be unable to do were the 

 ascent of the fluid entirely dependent upon 

 the action of the muscles of the organ.' 



The proboscis of the butterfly when coiled 

 up is about the same size as the fine hair- 

 spring of a watch, yet it is endowed with 

 thousands of muscular fibres and other minute 



6 



