180 THE MICROSCOPE. Dec. 



The malpighian (kidney) glands (fig. 7, m) sixty or 

 more in number are attached to the alimentary canal, 

 hard by the junction of the stomach (fig. 7, c) and short 

 intestine (fig. 7, d). The malpighian glands run through 

 the fat body which surrounds the hind intestine. 



To study the nervous system practically another speci- 

 men should be taken. It should be fixed by pins passed 

 through the upper part of the epicranium, and between 

 the mandibles. The clypeus and the front of the 

 epicranium must be removed. The super-oesophageal 

 ganglia or brain is supported by an internal skeleton of 

 chitin. From its upper part are given off the optic 

 nerves, and from its lower part, the nerves to the 

 antennae. 



To see the succeeding parts of the nervous system, the 

 head must be fixed upon its side and thegense, mandibles 

 first and second maxillte removed. Then the circura- 

 cesophageal commisureis shown in fig, 5 as two dots just 

 below the oesophagus. From this, nerves go to the 

 labrum. As usual, the two cords running from the brain 

 one on each side of the oesophagus, end below in a large 

 sub-oesophageal mass that supplies the mandibles, max- 

 illae and labrum, and, of course, belongs to the head. 



To see the succeeding parts, place the cockroach back 

 uppermost, remove the whole of the alimentary canal 

 from gizzard to rectum inclusive, and turn aside the crop. 

 The thoracic and abdominal chain of ganglia is thus ex- 

 posed. The thoracic are three pairs, and supply the 

 limbs. The abdominal are six pairs, connected by double 

 cords, and supply the abdominal organs and the integu- 

 ment. The sixth represents the nervous centers of the 

 sixth to tenth somites of the abdomen. 



The visceral or sympathetic system is represented by a 

 nerve given off from the circum-oesophageal commissure, 

 and supplying the labrum and a frontal ganglion. From 

 thiiiJ frontal ganglion a recurrent nerve passes over the 



