LEPIDOPTEEA. 



271 



end of one of these leaves has, it appears, been rolled back towards 

 the interior surface, in order to describe the first turn of a spiral, 

 which is then covered by many other turns (Fig. 282). Some 



Fig. 282. Oak leaf rolled perpendicularly. Fig. 283. Oak leaf rolled sideways 



leaves are rolled towards their exterior surface, others are rolled 

 towards their interior surfaces, but in a totally different direction. 

 The length or axis of the first roll is perpendicular to the principal 

 rib and to the stalk of the leaf, the axis of the latter parallel to the 

 same rib (Fig. 283). Work of this kind would not be very difficult 

 to perform for those who had fingers ; but caterpillars have neither 

 fingers nor anything equivalent to fingers. Moreover, to have 

 rolled the leaves is only to have done half the work : they must be 

 retained in a position from which their natural spring tends con- 

 stantly to draw them. The mechanism to which the caterpillars 

 have recourse for this second part of their work is easily perceived. 

 We see packets of threads attached by one end to the surface of 

 the roll, and by the other to the flat surface of the leaf. They are 

 so many bands, so many little cords which hold out against the 

 spring of the leaf. There are sometimes more than from ten to 

 twelve of these bands arranged nearly in the self- same straight 

 line. Each band is a packet of threads of white silk, pressed one 

 against the other, and yet we must remember all are separate."* 



Reaumur made the oak-leaf rollers work in his house. He has 

 * Me'moires pour servir a 1'histoire des Insectes, tome ii., page 210 (5e Mcmoire). 



