INSECTA. 247 



from the egg, are subject only to ecdysis and growth of wings during 

 an active nymph-hood, manifests, prior to exclusion, the same ana- 

 logies, which Oken expresses in the following words : — " Every fly 

 creeps as a worm out of the egg ; then, by changing into the pupa, it 

 becomes a crab, and, lastly, a perfect fly."* 



It is not, indeed, true that every flying insect creeps, as a worm, 

 out of the egg : all the Orthoptera and Hemiptera are excluded 

 under the type of the crab, i. e. with perfectly developed jointed legs, 

 eyes, antennae, and maxillary organs. The metamorphoses which the 

 locust undergoes in its progress from the potential germ to the actual 

 winged and procreative imago are nevertheless as numerous and 

 extreme as those of the butterfly. The differences are relative, not 

 essential ; they relate to the place in and the time during which the 

 metamorphoses occur, and to the powers associated with particular 

 transitory forms of the insect. The legs of the worm-like embryo- 

 locust were once unarticulated buds, like the prolegs of the cater- 

 pillar ; but the creature was passive, and development is not superseded 

 for a moment by mere growth ; these organizing processes go on si- 

 multaneously, or, rather, change of form is more conspicuous than 

 increase of bulk: the six rudimental feet are put to no use, but 

 constitute mere stages in the rapid formation of the normal seg- 

 ments, whicli attain their mature proportions and their armature of 

 claws and spines, before the egg is left. The first segment of the 

 originally apodal and acephalous larva is as rapidly and uninter- 

 ruptedly metamorphosed into the mandibulate and antennate head, 

 with large compound eyes. 



Thus developed, the young Orthopteran or Hemipteran issues forth 

 into active life. It may at once begin the great business of its ex- 

 istence, the propagation of its kind, as in the Aphis, and feed and die 

 without further change of form ; but generally the active crab-like 

 larvae are subject to three moults. After the first the larva has merely 

 increased in size ; but the rudiments of the wings begin to bud forth 

 beneath the second skin, and, after the second ecdysis, they present 

 themselves externally as small leaves, which cover the sides of the 

 first abdominal segment. When this active pupa or nymph again 

 moults, the insect attains its perfect condition ; the, at first, short, 

 soft, and thick wings rapidly expand to their full size, then dry in 

 the air, the circulation of the blood along the nervures is arrested, 

 and the metamorphosis of the individual is complete. Here, then, 

 we see that the pupa stage, which, in the butterfly, was passive and 

 embryonic, in the locust is active and voracious, whilst their re- 

 spective conditions in the larval state are reversed : the whole period 



* Naturgeschichte fiir Schulen, p. 577. 

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