ANATOMY 



495 



purpose of supplying food for their young. The crop — which 

 is situated in the anterior part of the abdomen — is the reser- 

 voir that contains this matter. The mode of disgorgement is 

 believed to be pressure exerted on the crop by contraction of the 

 abdomen. Salivary glands are present in remarkable variety. 

 The tracheal system possesses, in the higher winged forms, large 

 saccular dilatations situated at the side of the abdomen. The 

 nervous system is of peculiar interest on account of the high 

 intelligence of many of the members of this Order ; and on this 

 point of the anatomy, Brandt ^ has made rather extensive inves- 



FlG. 338. — Central nervous system 

 (supra-oesophageal ganglion and ven- 

 tral chain) of a worker ant, Cam- 

 ponotus ligniperdus. (After Forel.) 

 a, Cerebral hemisphere ; b, primor- 

 dial cerebral lobe or pedunculate 

 body (depressed so as to show other 

 parts) ; c, olfactory lobe (raised 

 from natural position) ; d, nerve 

 to labrum ; e, antennary nerve ; /, 

 scape of antenna ; c/, eye ; h, optic 

 nerve ; i, longitudinal commissures 

 connecting the hidden sub-oesopha- 

 geal ganglion with k, the prothoracic 

 ganglion ; /, mesothoracic, m, meta- 

 thoracic ganglion ; s, ganglion of the 

 petiole ; n, nerve from petiole to 

 other part of abdomen ; r, q, o, 2nd, 

 3rd, 4th abdominal ganglia ; j), ter- 

 minal nerve to cloaca ; t bases of 

 legs. 



tigations, having examined it in the adult of seventy - eight 

 species, and in the larva of twenty-two. In the adult there are 

 two cephalic — the supra- and the sub-oesophageal — two or three 

 thoracic, and from three to seven abdominal ganglia. The bees, 

 wasps, and some other of the Aculeata have only two thoracic 

 ganglia, while some ants have three. The supra-oesophageal 

 ganglion is very large. The most remarkable fact revealed by 

 Brandt's investigations is the great difference that exists between 

 the sexes and the worker caste in the same species. The pedun- 



1 OM. Ac. Paris, Lxxxiii. 1876, p. 613, and Ann. Mag. Nat. Hist. (4) xviii. 1876, 

 p. 504 ; also Horae Soc. Moss. xv. 1880, pp. 20 and 31. 



