LOCUST 185 



lie ? How do they compare in shape and size 

 with the thoracic ganglia ? 



How does the nervous system of the locust 



compare in structure with that of the lobster ? 



What resemblances and differences do you find ? 



Make a diagram of the nervous system as seen from 



above. 



m. The thigh, muscles. — With a pair of line scissors or 

 a sharp scalpel cut the integument along the pos- 

 terior edge of the femur of one of the third pair 

 of legs, carefully turn back the outer flap thus 

 formed, and notice the arrangement of the mus- 

 cles within this segment. Judging from the di- 

 rection of the groups of fibres, how many distinct 

 muscles does this segment contain ? Are any of 

 the groups arranged to correspond with the pe- 

 culiar tile -like pattern seen on the outer surface 

 of this segment ? 



PHYSIOLOGY 



Many of the following questions may be answered as 

 well from a study of dead as from living specimens. 



a. The lody as a whole. — Is its shape at all related to 

 the animal's mode of life ? What advantages 

 arise from having the body made of segments? 

 What reasons can you give for the grouping of 

 the segments into regions ? Why are the append- 

 ages jointed ? What appears to be the principal 

 function of each region, as determined from its 

 structure and appendages ? Has the insect any 

 skeleton ? If so, how does it compare structurally 



