DESCRIPTION OF ILLUSTRATIONS. 
195 
FIG. 
21. Section through thorax of drone. — levator alarum; 
depressor alarum; antagonist of depressor; ^/, pos- 
terior wing muscle; air sacs; gland system No. 3; 
neck; //, mesophragma; ?, spiracles 
22. Abdomen of worker, — petiole; <r, y, rings; 
g, pygidium 
23. Longitudinal section of bee’s head. — a., mentum; 
submentum ; r, rods; y lora; ligula; f g., labial 
palpus; forked pillar; i, pharynx; clypeus; 
/, antenna ; 7 Ji, spoon ; n, paraglossie ; 0, ocellus ; />, 
brain ; r, neck ; j', salivary duct systems, 2 and 3 ; /, sali- 
vary duct system, i ; u, upper lip 
24. Diagram of transverse section of head of bee. — c, rods; 
h, mesocephalic pillars; r, neck 
25. Tracheae. — a, external serous membrane ; internal 
mucous membrane ; r, spiral fibre 
26. Aerating system 
27. Dorsal vessel 
28. Ventricles and valves. — opening into ventricle; 
valve between ventricles 
29. Nervous system. — brain; /;, first thoracic ganglion, 
connected with fore legs ; r, ganglia connected with 
middle and hind legs, and wings; y last abdominal 
ganglion ; <?, compound eyes ; y sub-oesophageal gan- 
glion ; oesophageal collar 
30. A, ganglionic cells and nerves; B, nerves enclosed in 
sheath; C, ganglionic and nervous cords 
31. Brain deprived of its covering 
32. Same viewed from top of Fig. 31 
33. A, bundle of muscular fibres; B, muscular fibre; <2, ex- 
panded; contracted 
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