52 maoovcsrnom. 



former days, the metamorphosis of an insect is nothing more 

 than.a repeated casting off of its external skin, the perfect insect 

 existing all the while in its proper form, beneath and within its 

 different external wrappers. Bat surely, as Professor Rymer 

 Jones remarks, it can be no more necessary to suppose the pre- 

 existence of so many skins in order to explain the monks of a 

 caterpHar, and its subsequent changes to a chrysalis and a 

 Butterfly, than to imagine that we ourselves have several skins 

 oae beneath the other, because, when the cuticle is removed 

 by the application of a buster, a new layer of epidermis is again 

 and again renewed. The error arises from a mistaken ioea, 

 that the metamorphosis of the insect is something singular and 

 exceptional in the animal world, combined with a misconception 

 as to the true nature of the epidermic investment. The proper 

 explanation of the phenomena appears to be this, that the suc- 

 cessive changes which the insect undergoes are, in principle, Hoe 

 same as obtain amongst most other creatures in the earlier stages 

 of their existence ; and that the repeated moults and changes of 

 form are due to the living skin or cntis beneath the external 

 epidermis gradually developing itself, and expanding into vari- 

 ously-shaped organs, in accordance, in every case, with the law 

 of being, if we may so speak, of each individual species. The 

 popular notion is, no doubt, by far the most attractive of the 

 two ; but, unfortunately, nature and truth do not always square 

 with our ingenious fancies, which injure quite as often as they 

 advance the cause of science. 



Let us pass, however, from this somewhat dry and abstruse 

 topic to the history of an insect familiar to all our readers, and 

 which has long occupied the attention of naturalists. 



The Aphidet, or plant lice, the " green fly " of the gardener, 

 have as wonderful a history as any members of the insect tribes ; 

 and with a small expenditure of trouble our readers may trace 

 the entire wonderful history for themselves. It appears that, 

 in autumn, the swarms of Aphides which infest our plants are 

 composed of both male and female insects, which, after pairing, 

 and the deposition of the eggs by the females for a fresh brood, 

 speedily die. In the following spring, as soon as the sap begins 

 to flow, the eggs which have survived the rigours of winter are 

 hatched, and a brood of fully-formed young lice is produced, which 

 beginning immediately to pump up sap from the tender leaves and 



