31G The Ohio Journal of Science [Vol. XVI, No. 7, 



Tracheal System. (PL XXII, Fig. 33). 



The Tracheal System consists of the main trunk (m. t.) 

 system connected with the spiracles (spi.). There are in most 

 forms nine pairs of spiracles; two thoracic, and seven abdominal 

 (I-VII), although in some species the abdominal number may 

 be only six. The thoracic spiracles (t. spi.) are at first rather 

 difficult to detect, but may be found below the wings on the 

 episterna as two small, unprotected holes. On the abdomen 

 the spiracles (ab. spi.) appear as small, elongate, narrow holes, 

 located on the anterior halves of the segments, near the pleural 

 membranes. Each spiracle connects with the main trunk 

 system by a short tube. 



The main trunk system (m. t.) comprises the two lateral 

 tubes, which run down the sides of the body and anastomose. 

 The two longitudinal trunks are connected by transverse 

 trachea in the meso- and meta-thorax. The anastomosis in 

 the thoracic trachea is best shown by reference to the Figure 

 (PI. XXII, Fig. 33). Two large transverse tubes connect the 

 longitudinal trunks in the mesothorax, while in the metathorax 

 the two transverse tubes do not open directly into the main 

 trunks, but connect with the spiracle tube. A small tracheal 

 tube runs between the two thoracic spiracles and gives off the 

 branches which run to the wings. In the nymphs these tubes 

 are very evident, although in the adult they are not so prom- 

 inent. At the caudal end of the body the two trunks are in 

 close relationship by means of their smaller branches, but no 

 distinct tracheal connection is seen. 



From the main longitudinal trunks arise the three systems 

 of branches, the dorsal, visceral and ventral, which ramify 

 through each segment, and portion of the body. Two strong 

 branches are seen in the head, and supply the antennae, mouth- 

 parts and the viscera of the head with trachea. Branches 

 of the dorsal system can frequently be found in the dorsal 

 muscles of the thorax, and in the peripheral region of the dorsum. 

 The visceral system of branches supports the digestive apparatus 

 and the reproductive organs, while the ventral system is closely 

 connected with the nervous system and the ventral musculature. 



