INSECTS : THEIB FEET. 123 



the style-flag; and hence, as these insects are not so 

 commmon as many others, this Iris is often barren, or 

 bears imperfect seeds."* 



The legs and feet of Caterpillars are constructed on 

 a very different plan from those of perfect insects, as you 

 may see in this living Silkworm. The first three segments 

 of the body, reckoning from the head, are furnished each 

 with a pair of short curved limbs set close together on the 

 under side. These represent the true legs of the future 

 moth, and show, notwithstanding their shortness, four 

 distinct joints, of which the last is a little pointed horny 

 claw. The whole limb resembles a short stout hook. 

 Then two segments occur which are quite smooth be- 

 neath, and destitute of limbs ; and then on the sixth we 

 begin to find another series, which goes on regularly, a 

 pair on each segment, to the eleventh and final one, with 

 the single exception of the tenth segment, which is again 

 deprived of limbs. 



But these organs are of a very peculiar character. They 

 have no representatives in the mature insect, but dis- 

 appear with the larva state ; and they are not considered 

 limbs-proper at all, but merely accessory developments of 

 the skin to serve a special purpose. They are sometimes 

 called claspers, sometimes false-legs, but more commonly 

 pro-legs. 



Each consists of a fleshy wart, which is capable to some 

 extent of being turned inside out, like the finger of a 

 glove. Partly around the blunt and truncate extremity 

 are set two rows of minute hooks, occupying the side next 

 the middle line of the caterpillar in a semicircle along the 

 margin. These hooks arch outward as regards the axis 

 of the pro-leg, though the majority of them point towards 

 the medial line of the body. The double row is somewhat 



* Penny Cyclop., art. Bee. Becent researches of Mr. Darwin and 

 others have shown that the agency of insects in the fertilisation of 

 plants is very far more important than had been suspected. 



