INTRODUCTION. 85 



pour ainsi dire, 1'insecte 1'applique contre la feuille, 

 il est asses gluant pour s'y coller : il peut bien avoir 

 &e tire droit d'une partie de la feuille a 1'autre, mais 

 il ne S9auroit avoir ete asses tendu pour faire un 

 effort capable de ramener une des deux parties de 

 la feuille vers 1'autre. Je S9ais que ce fil, quoique 

 extremement delie, a quelque force; je lai vu en 

 bien de circonstances, suspendre la chenille en Tair, 

 mais il n'a pas ete possible, que quand il a ete attache 

 avec le degre de tension necessaire pour forcer une 

 des parties d'une feuille a* s'approcher de 1'autre. 

 Si apres avoir ete file, il se raccourcissoit en sechant, 

 ce raccourcissement le mettroit en etat d'agir; 

 mais ou peut aller le raccourcissement d'un fil si 

 court? Combien seroit petite la courbure qu'il 

 pourrait donner a la feuille* !" It is very likely, 

 however, that the thread suffers some contraction as 

 the moisture evaporates by the action of the air, and 

 however slight that contraction may be, that it co- 

 operates with other causes to produce the curvature. 

 The only other means which the insect has been 

 observed to employ, are drawing the threads towards 

 itself by its fore legs, and hanging upon them with 

 the whole weight of its body. These threads are not 

 placed at random, but arranged in small bundles or 

 fascicles, each of which consists of two parallel rows, 

 crossing each other in the centre. When the insect 

 has formed the lower series, it passes to the other side 

 and spins the second, making use of the former, while 

 so doing, as a kind of platform for the support of its 

 * Reaumur, Mem. ii. p. 215. 



