THE INTERNAL ANATOMY OF INSECTS 



151 



the front trachea (Ti) and the hind trachea (Te) ; these two branches 



reunite a short distance beyond the end of the chordotonal organs. 



It is an interesting 

 fact that these large 

 tracheas of the legs 

 containing the chor- 

 dotonal organs open 

 through a pair of 

 supemumery spir- 

 acles, differing in this 

 respect from the tra- 

 cheae of the other legs. 

 The spaces of the 

 leg. — By reference 

 to Figure 172, it will 

 be seen that the two 

 branches of the leg 

 trachea occupy the 

 middle space of the 

 leg between the two 

 tympana (Tie and 

 ■^ Tii) and separate an 

 outerspace, theupper 

 one in the figure, from 

 an inner space. The 

 outer space (E) con- 

 tains a chordotonal 

 organ, of which the 

 scolopale is repre- 

 sented at S ; and the 

 inner space contains 

 small tracheae (t), 

 muscles (m) , the 

 tibial nerve (Ntb), 

 and a tendon (Tn). 

 The interstices of the 

 outer andinnerspaces 

 are filled with blood. 



In the outer space some leucocytes and fat-cells (Gr) are represented. 

 The supra-tympanal or subgenual organ. — In the outer space of 



the tibia, a short distance above the tympana, there is a ganglion (Fig. 



Fig. 171. — Longitudinal section of a fore tibia of 

 Decticus verrucivorus (From Berlese after Schwabe). 



