THE CAPRICORN 



gives the grub something to push against. At the same 

 time the flattening of the front pads, by decreasing the 

 size of the grub, allows it to slip forward and take half 

 a step. Then, to complete the step, the hind-quarters 

 must be brought up the same distance. With this object 

 the front pads fill out and provide support, while those 

 behind shrink and leave room for the grub to draw up 

 its hind-quarters. 



With the double support of its back and stomach, with 

 alternate swellings and shrinkings, the animal easily 

 advances or retreats along its gallery, a sort of mould 

 which the contents fill without a gap. But if the pads 

 grip only on one side progress becomes impossible. 

 When placed on the smooth wood of my table the animal 

 wriggles slowly; it lengthens and shortens without pro- 

 gressing by a hair's breadth. Laid on the surface of a 

 piece of split oak, a rough, uneven surface due to the 

 gash made by the wedge, it twists and writhes, moves 

 the front part of its body very slowly from left to right 

 and right to left, lifts it a little, lowers it, and begins 

 again. This is all it can do. The rudimentary legs 

 remain inert and absolutely useless. 



II 



THE grub's sensations 



Though the Capricorn-grub possesses these useless 

 legs, the -germs of future limbs, there is no sign of the 



[213] 



