5$ .i\rs. 



the mesothoracic ganglion arises a pair of so-called alar nerves, which 

 innervate the great longitudinal and transverse vibratory muscles of the 

 wings. The musculature of the epinotum, petiole and postpetiole is 

 supplied by the tir>t to third abdominal ganglia, the two first of which 

 are fused with the metathoracic ganglion. The fourth abdominal ( first 

 gastric in the MyrmicicUe) remains in the segment to which it belongs, 

 but lies at its extreme anterior edge. As both this and the succeeding 

 gastric ganglia have been secondarily drawn forward, the pairs of 

 nerves which they give off run obliquely backward, to their innerva- 

 tions. Janet (1902) has found that each of the two nerves arising 

 from each of the four anterior gastric ganglia divides into a dorsal and 

 a ventral trunk. The former sends off a sensory nerve to the corre- 

 sponding dorsal quadrant of the segment and three motor nerves to its 

 three muscles, the latter a sensory nerve to the ventral quadrant and 

 six motor nerves to as many muscles. The sensory nerves go to the 

 sense-hairs of the integument. The terminal (fifth gastric) ganglion, 

 formed, as we have seen, by a fusion of the eighth to tenth abdominal 

 ganglia, sends off four pairs of nerves, the first to the sense organs and 

 muscles of the stylets of the sting, the second to the sense organs and 

 muscles of the gorgeret, the third to the anal sphincter and papilla, and 

 the fourth to the walls of the hind gut. 



The Sympathetic. This consists of several minute ganglia and 

 nerves connected with the central nervous system and supplying the 

 musculature of the alimentary tract. It is, to judge from Janet's 

 account of Mynnica (1902), well developed in ants and not unlike 

 that of other insects. It may be said to embrace two systems, one 

 supraintestinal and supplying the dorsal and lateral portions of the 

 digestive tract, the other subintestinal and lying beneath the intestine 

 and above the ventral nerve-cord. The supraintestinal system may be 

 divided into an unpaired and a paired portion. The former begins in 

 the small frontal ganglion (Fig. 27, fi/h. which lies anterior to the 

 brain, to which it is joined by a pair of connectives. According to 

 Tanet, these connectives arise in the protocerebrum, but other authors 

 believe that they are of tritocerebral origin. The frontal ganglion 

 sends a pair of coalesced nerves to the supero-anterior wall of the 

 pharynx and a much stouter unpaired nerve, known as the recurrens 

 ( rcii ), downward and backward along the dorsal wall of the pharynx, 

 to a ganglion (the hypocerebral, lies), which lies on the oesophagus 

 just beneath the protocerebrum. Besides innervating the oesophagus 

 this ganglion sends back a pair of long, slender connectives (sym) 

 along the sides of the oesophagus and crop to the point where the 

 latter contracts to form the gizzard. Here each connective termi- 



