a0... ie 
tr. Foggo on an Insect foundin the wood of a Table. 289 
been considered quite analogous to the well-known facts of 
reptiles being found alive in solid rocks, and have been re- 
ferred to the same cause, a temporary suspension of the vital 
functions. The circumstances, however, are essentially 
different. We have reason to believe, that the reptiles were 
enclosed in the same state as when they were discovered. 
ing to ascertain in what state the animal has existed during 
its confinement, and what are the causes which have retard- 
ed its advancement to maturity. A late author had conjec- 
tured, that the ovum from which the insect was produced, 
having been prevented from undergoing the necessary evolu- 
tion, had retained its animating principles till summoned into 
action by some change in its relation to external objects ; 
and further, that it might have lain dormant for an indefinite 
space of time. The same author has likewise endeavoured 
to explain in this manver the periodical visitation of the lo- 
cust, palmer worm, Hessian fly, &c. with the additional hy- 
pothesis that certain modificatious of the atmosphere may be 
peculiarly favourable for their production. This explanation, 
however, is liable to several objections. It is difficult to 
conceive any cause that could operate year after year in 
preventing the animal from arriving at maturity, and that too, 
apparently in the very situation selected by the instinct of 
the mother. Moreover, on examining the cavity in which 
this animal was lodged, it is evident that, while within the 
tree, it must have passed its life in an inert state. This isa 
fact which is searcely consistent with our knowledge of the 
that the larva penetrated the tree in order to prepare for 
becoming a chrysalis, and having at last assumed its perfect 
form, emerged into light in the usual time. That the insect 
made its appearance in the ordinary period peculiar to the 
species, is rendered probable from several collateral facts. 
It is well known that several species of iusects remain in the 
chrysalis for many years; that the locust appears in numbers, 
once only in 17 years, and the palmer worm in 30 years, yet 
these are cycles not recognised by meteorologists. The tribe 
Urocerata is also subject to periodical swarming, ‘et pa. 
a 1X%.-—No. 2. 
raissent certaines années en telle abondance quils ont été pour 
V 37 
