LEGS. 139 



along the smoothest surfaces, and it makes no dif- 

 ference whether the body is upwards or down- 

 wards. To enable it to do this, its feet are so 

 made, that when placed flat, a slight vacuum may 

 be produced in the centre, which holds the edges 

 fast, just in the same way that the hand sticks to 

 a wetted slab, when the palm is a little raised, and 

 as boys lift up stones by a piece of moistened lea- 

 ther with a string through it. 



Questions. 



How may we obtain an idea of the trunk or proboscis of 

 insects ? 



For what is this used by such insects as feed on honey, as 

 the butterfly and bees ? 



What shape is the trunk in the common house-fly 1 



What insects use their trunk both as a borer and a pump ? 



Are the wings of insects of very beautiful texture ? 



What insects have particularly delicate wings, and how 

 are these defended ? 



With what are the wings of butterflies covered ? 



How are these wings moved 1 



How many legs are insects provided with ? 



What enables the fly to walk on smooth surfaces ? 



Can you describe how this is done ? 



