i6 PHYLUM ARTHROPODA 



portion is the oesophagus ; the middle and largest portion is the 

 stomach ; the narrow portion back of the stomach is the intestine, 

 which communicates with the anus. In the forward portion of 

 the body cavity, along the wall of the oesophagus, is a pair of del- 

 icate, tubular salivary glands which extend forward and conamu- 

 nicate with the mouth. Note and trace the course of the much 

 larger, tubular silk glands on the ventral body wall ; they are also 

 a single pair and communicate with an opening in the labium. 



Find and carefully trace the course of the six Malpighian tubes, 

 which lie along the stomach and join it at its posterior end. 



Exercise 3. Draw an outline of the opened animal on a scale of 6, 

 showing the organs above described as far as they have been ob- 

 served. Represent the segmentation and show accurately the posi- 

 tion of the organs in their proper segments. 



Sever the oesophagus and remove the stomach and the intestine 

 from the body. Study the nervous system. Note the arrangement 

 of the tracheae with reference to the spiracles. Note the longitu- 

 dinal muscle bands which form a part of the body wall ; note also 

 their segmental arrangement. 



Exercise 4, Draw an outline of the opened body on a scale of 6, 

 showing and numbering the segments. Draw in it the nervous 

 system, representing accurately the number of ganglia and plac- 

 ing them in the proper segments, together with the tracheae and 

 muscles. 



The reproductive system consists of two small sexual glands and 

 a duct leading from each. There is no external pore. 



