14 FOREST ENTOMOLOGY. 



sap of the plant before the juice is taken up by the proboscis. 

 At c we have the long crop, and below this we have the gizzard, 

 which organism in some species is a favourite object for the micro- 

 scope. Then we have a stellate arrangement of the csecal tubes or 

 blind tubes ; and proceeding from this there is the stomach, which 

 is simply a tube. At k we have the kidney tubes, and then the 

 small and large intestine, ending in the rectum and anus. In fig. 19 



Fig 17.— Trachea of butfcvfly. (Flatters & Garnett.) 



we have a representation of tlie heart, which is a long muscular tube 

 separated by valves. 



Having now considered the various structural details of an insect, 

 it may be well to turn briefly to the reproductive organs, the func- 

 tions of which serve to perpetuate the race. Insect reproduction 

 may be either sexual or asexual. In the former, the union of two 

 dissimilar cells is required — viz., a small active (male) sperm cell 

 (spermatozoon) with a large (passive) female cell (ovum) for the 

 production of new individuals. In the latter class, female cells or 



