MODES OF EMERGING FROM PUP-K. 327 



and forwards, and shifting tlieir hold till she was 

 entirely extricated, when they left her to recover her 

 strength by herself ' Probably,' say our authors, 

 ' the extreme length of the two pair of hind-legs of 

 these animals may render such assistance necessary 

 for their extrication.'* We, however, imagine that 

 Captain Percy's instance was accidental and anoma- 

 lous; for the insect having already extricated her head, 

 shoulders, and fore -legs, all the difficulties were sur- 

 mounted. From the insect being so very common, 

 also, tiie circumstance of such assistance, if it did 

 happen, must be matter of frequent observation; but 

 we iiave witnessed a considerable number of several 

 species of this tamily undergo the change without any 

 assistance whatever.! 



The best ascertained case of assistance occurs 

 among ants, and was first observed by the accurate 

 Swedish naturalist De Geer, though the best ac- 

 count of it is given by the younger Huber. ' The 

 greater part of the pupre,' says he, ' are inclosed in 

 a tissue spun by themselves before their change; 

 but they cannot, like other insects, liberate themselves 

 from this covering by effecting an opening in it with 

 their teeth. They have scarcely the power of mov- 

 ing; their covering is of too compact a texture, and 

 formed of too strong a silk, to allow of their tearing 

 it without the assistance of the workers. But how do 

 these indefatigable attendants ascertain the proper 

 moment tor this process? If they possessed the fa- 

 culty of hearing, we might imagine they knew the fit 

 time, from some noise produced in the interior of the 

 prison bv the insects whose development has com- 

 menced; but there is no indication favouring this 

 opinion; it is probable they have a knowledge of it 

 from some slight movements that take place within, 

 which they ascertain through the medium of their 



* Intr. iii, 286. + J. R. 



