42 ANIMAL ACTIVITIES. 
hairs which seem to increase their sensibility, and they 
are connected with the nerve-centres within the body, 
as are the other organs of sense. 
Movements. In addition to the motion called forth 
by irritation of the sense-organs, the grasshopper is 
evidently able to move on his own account. He can 
walk, fly, or jump where and when he wishes. The 
Fic. 45.—The Stridulating Organ of a Cricket. u, large vein; 4, 
roughened cross-vein; c, membrane, 
adaptation of the legs to the mode of life needs no 
comment. The structure of the wings, however, may 
be briefly considered. The wings are outgrowths of 
the hard exoskeleton. They are composed of a frame- 
work of double tubes over which is stretched a mem- 
brane. The inner tube of one of the veins carries air. 
The outer tube surrounding this is filled with blood. 
Thus the wing becomes an organ of respiration as well 
as an organ of flight. Lightness and strength are also 
obtained at the same time. 
Comparison of Grasshopper and Cricket. Crickets 
are easily collected. They may be studied in the same 
way as the grasshopper. In writing notes concerning 
the cricket, make use of the new descriptive words 
learned while studying the grasshopper. Write in your 
note-book only such facts as can be made out from the 
specimens. At the top of the page in your note-book 
write ‘‘Grasshopper and Cricket’’. Draw a vertical 
