H4 HOUSE, GARDEN, AND FIELD 



intended for firm ground ? Animals still smaller than the 

 lark, which have to run about on grass, sometimes have 

 legs of amazing length in proportion to the size of the 

 body. The weight of a harvestman or a daddy-long-legs 

 is insufficient to press down a single blade, and if its legs 

 were not very long and jointed in many places, it could 

 only travel over a meadow by continually ascending and 

 descending, or else grasping every bit of grass that came 

 in its path. 



XXII. THE CHEESE-HOPPER. 



Last October, being interested at the time in mites, I 

 sent to a cheesemonger for a pound of mitey cheese. In 

 it were observed, besides the mites, a few small white 

 worms, which were recognised as the grubs of the cheese- 

 fly. They grew steadily all the winter through, and 

 proved very useful in the laboratory, whenever we had 

 occasion to study the structure of the headless, footless 

 larvae which are called maggots. The grubs are sluggish, 

 and move slowly about the cheese by wriggling, and occa- 

 sionally by grasping inequalities of the surface with their 

 mouths. When they desire to change their quarters, they 

 are able to leap several inches at a time, after a fashion 

 which was described by Swammerdam more than two 

 centuries ago. Bending its body into a semicircle, the 

 larva grasps the last segment with a pair of strong hooks, 

 which can be protruded from the mouth. All the muscles 

 are strained in the effort to straighten the body, but the 

 hooks keep their hold until the muscles are contracted to 

 their uttermost. The circle narrows to an oval, and the 

 oval closes up till its sides meet. Then the hooks relax, 

 the larva suddenly reverses its curvature, and presses the 

 ground with such force as to jerk the body into the air 

 several inches. If possible, the body is arched in a vertical 

 plane, the head and tail being turned downwards, but on 

 a smooth, flat surface the circle is horizontal. The 



