268 ZOOLOGY. 



stances? Do you find any hint as to the method of their pro- 

 duction ? 



5. Do you detect any movements which suggest respiration? 

 Rate? (Find spiracles in the thorax and abdomen.) 



6. Supply hungry animals with fresh leaves ^nd study the 

 feeding process. Dip the leaves in various solutions and 

 notice whether it makes any difference to the grasshopper. 



If alcoholic material is used for the following morphological 

 studies it should not be allowed to become dry. If dipped in 

 a mixture of glycerine and 50 per cent, alcohol, specimens 

 will not dry so rapidly. 



The sexes differ, particularly in the abdominal region. 

 Procure specimens thus differing by examining a number of 

 individuals, and keep both kinds for comparison. Sketch 

 dorsal, lateral and ventral views of each (especially in the 

 regions of difference). 



External Features. Study the following points : 



1. The regions of the body. 

 Head; thorax; abdomen. 



What are the signs of segmentation in these three 

 regions? Where is it most clearly indicated? Where 

 are the segments most similar? 



2. Abdomen. 



Number of segments (differs in male and female). 

 Dorsal and ventral plates. Are they equally developed in 



all segments. 

 Appendages : which segments possess them ? 



Ovipositors (paired outgrowths found only in the 



female). 



Anal cerci (examine the male). Are they found in 

 the female? To what segments do these appendages 

 belong? 

 Spiracles (small openings at the side of the segments) ; 



number and distribution? 



Tympanic membrane, at the sides of the first abdominal 

 segment. 



