180 HOUSE, GARDEN, AND FIELD 



that the eggs are laid in the earth, and hatch out in spring. 

 Full-grown frothing hoppers continue to feed on the juices 

 of plants, and occasionally exude drops of liquid from the 

 intestine, but they never blow bubbles. 



Naturalists who can use the microscope will find the 

 hind legs of the full-grown frothing hopper an interesting 

 study. Notice the spines which hinder the foot from 

 slipping at the moment of leaping, and compare them with 

 the corresponding parts of a cricket (see p. 187). 



XXXIII. ANIMAL GLOBES. 



The ready and complete adaptability of animals to 

 external circumstances is shown by the resemblances 

 which like conditions produce in the most diverse animals, 

 and the differences which unlike conditions produce in 

 nearly related ones. Let me illustrate this general state- 

 ment by examples of animals which are defended by 

 their globular form, and often by spines as well. 



No common quadruped is better protected from its 

 enemies than the hedgehog. The sharp spines and the 

 habit of rolling up are first remarked. On dissection we 

 discover a dome of circular skin-muscles on the back, 

 which is bordered on all sides by a thick muscular rim. 

 When the hedgehog walks, the mass of circular muscles 

 forms a hump upon his back, but when he is alarmed, he 

 draws the head and legs within the rim, which tightens 

 like an elastic ring surrounding the mouth of a bag. The 

 mere act of rolling up erects the spines, and makes them 

 point stiffly in all directions. The prickly sphere rolls 

 when pushed, and can neither be bitten nor grasped. A 

 hedgehog can defy dogs or any other predatory animals. 

 It can also when rolled up drop safely from a height of 

 several feet, and adopts this method of getting down a 

 low cliff. Very like the hedgehog in outward appearance, 

 and covered in the same way with strong sharp spines, 



