212 LIFE AND HER CHILDREN. 
Next behind the head of the grasshopper comes 
his chest or thorax, formed of three rings, each of 
which bears a pair of legs, and the two hinder ones 
two pairs of wings, while the shoulders are covered by 
a shield. Behind this again comes the ringed abdomen 
which he can curve and bend at will. Now, on looking 
carefully along the sides of these rings you will see a 
dark spot (s) on each, and a magnifying glass will 
show that this spot is a round plate with a slit in the 
middle (s, Fig. 
73). These are 
the breathing - 
holes or spiracles 
of the grasshop- 
per, and if you 
S, Spiracle or breathing-plate (j, Fig. 72), were to CUt his 
with the slit in the centre which opens to take body open under 
in air. 
T, Part of the breathing-tubes or trachea:, water you WOUld 
showing the spiral thread which keeps the see hundreds of 
tubes in their round shape. minute gHstening 
tubes called trachea (T, Fig. 73), running in all 
directions and ending in larger tubes, each of which 
is joined to one of these breathing -holes. These 
tubes are formed of two layers, between which is 
wound round and round a stiff wiry thread (see Fig. 
73), which keeps the tube in shape, just like the spiral 
wire which they put into india-rubber tubing. The 
glistening is caused by the air which has been taken 
in at the breathing holes, and fills all the tubes. 
If instead of cutting open the grasshopper you 
keep him alive under a glass, you may watch his 
abdomen moving up and down and pumping the air 
in at the slits, and that air will pass all through his 
