190 STATES OF INSECTS. (Larva.) 
in the scale to the Serpent tribe*, which at certain pe- 
riods disengage themselves from their old integument, 
and start forth with that new and deadly beauty so fine- 
ly described by the Mantuan bard :— 
“So from his den, the winter slept away, 
Shoots forth the burnish’d snake in open day; 
Who, fed with every poison of the plain, 
Sheds his old spoils and shines in youth again: 
Proud of his golden scales rolls towering on, 
And darts his forky tongue, and glitters in the sun.” 
Pitt. 
In these the new skin, I imagine, is formed under the 
old from the rete mucosum ; but in insects, as I formerly 
stated°, since the time of Swammerdam it has generally 
been believed by entomologists, that the larva includes a 
series of cases or envelopes, one within the other, con- 
taining in the centre the germe of the future perfect in- 
sect, whose development and final exclusion take place 
only when these cases have been successively cast off. 
This hypothesis, as was explained to you on a former 
occasion’, has been controverted by a late writer, Dr. 
Herold; who affirms that the skins of caterpillars are 
also successively produced out of the rete mucosum. I 
have however, I hope, satisfied you that the old system 
is most consonant to nature and probability: but as we 
are now to enter at large upon the Moults of insects, it 
@ In the human species, after certain fevers a simultaneous and 
total moult, if the term may be so applied, takes place. I experi- 
enced this myself in my boyhood; when convalescent from Scarlatina, 
the skin of my whole body, or nearly so, peeled off. 
> The translator, more ignorant of natural history than his author, 
has turned the “dinguis micat ore trisulcis” of Virgil, into “ darts 
his forky sting.” 
© Vou. I. p. 70: 4 See above, p. 52—. 
