188 HOW TO KEEP BEES 



and extends from one end to the other. The heart 

 (h) is a tube open at both ends, and lying between 

 the alimentary canal and the muscles of the back. 



The central part of the nervous system (n) is a 

 series of small masses of nervous matter, connected 

 by two longitudinal chords; one of these masses, 

 the brain, lies above the alimentary canal; the others 

 are situated, one in each segment, between the 

 alimentary canal and the ventral wall of the body; 

 the two chords connecting these masses, or ganglia, 

 pass one on each side of the oesophagus to the brain. 

 The reproductive organs (r) lie in the cavity of the 

 abdomen and open near the hind end of the body. 

 The respiratory organs are omitted from this dia- 

 gram for the sake of simplicity. 



The respiratory system. — The most striking pecu- 

 liarity in the structure of insects is the form of 

 their organs for breathing, for they do not breathe 

 through the mouth as we do. If an insect be care- 

 fully examined, there can be found along the sides 

 of the body, a series of openings; these are the 

 openings through which the air passes into the respir- 

 atory system, and are termed spiracles. The spir- 

 acles of the honey-bee are small, and are not easily 

 found by one not trained to look for such things; 

 but if the reader will examine the sides of one of our 

 larger caterpillars, he will have no trouble in seeing 

 them. Typically, there is a pair of spiracles, one 

 on each side of the body, in each of the body-seg- 

 ments, but they are lacking in the head and in some 

 of the other segments. The spiracles lead into a sys- 



