ANATOMY OF THE BEE. 



507 



other pairs of such openings occur in the 

 thorax; but the last of these, being in the 

 propodeum, really belongs to the abdomen. 

 Thus there are in all ten pairs of breathing 

 apertures, and they are called the spiracles. 

 None occur on the head. The tracheal 

 tubes given off from the air-sacs branch 

 minutely to all parts of the body and pene- 

 trate into most of the tissues. Hence oxy- 

 gen is carried directly to the cells that use 



it, and the blood of insects is thus relieved 

 of the work of distributing it— one of its 

 principal functions in vertebrate animals. 

 The respiratory movements are produced by 

 muscles of the abdomen. 



The life processes of the cells of the body 

 result in the formation of products excreted 

 by the cells into the surrounding blood. 

 These products nre poisonous to the system 

 unless immediately changed into simpler 



,Lbl 



LbL, 



B 



St v| \ , j 1^ r^ 



Lr Pj X/ 



^<siis^ ' £■' Mt 



^^ f Lb Pip 



RMcl 



From Bulletin No. 18, "The Anatomy of the Honey-bee," by Snodgrass, Bureau of Ent.. Dept. of Ag.. Washington, D. C. 



channel (Lum) opeu below along- the groove (fc), i-nc iu,cii.«,i .x^« ^■, '"/^,";;>,y; ~-V""-' f t,-_,,,.. .^/j lateral 

 F, distal^end of.rSentum (MO, dorsal._ ehowin^^^openmg^^^^^^^ 



paraglossa; Pig, palpiger; g, inner wall of glossa ,+i„^, 



glossal rod; SaMO, opening of salivary duct; Smt, submentum; St, stipes. 



