THE COCKROACH. 361 



for a week or more, before depositing it. The young leave 

 the eggs as minute active insects, colorless, except for the 

 large dark eyes. Before they are hatched they acquire eyes, 

 antennae, gnathites, legs, and short cerci, which differ only in 

 detail from those of the perfect Blatta, into which the larva 

 passes by successive ecdyses. According to Cornelius (I. c, 

 p. 29), the Cockroach undergoes seven ecdyses : the first im- 

 mediately on leaving the egg, the second a month later. 

 After the second ecdysis the insect sheds its skin only once 

 a year ; so that it attains its adult condition only in its fifth 

 summer. The chitinous cuticula splits along the median line 

 of the tergal aspect of the head, thorax, and abdomen, before 

 it is cast. 



Thus the Cockroach is said to be an insect without meta- 

 morphosis. For although the male, in the later stages of its 

 growth, acquires wings, and thus does become very sensibly 

 metamorphosed from a merely cursorial animal to one which 

 has, at any rate, the capacity for flight, there is no period in 

 the life of this insect in which the larva passes into a resting 

 condition, during which it takes no food, and in the course of 

 which it develops its wings. In other words, the Cockroach 

 passes through no pupa-state, which the insect enters as a 

 larva, and leaves as an imago, such as is so well knowm to 

 occur in the course of the development of Moths and Butter- 

 flies. The term metamorphosis, in its technical entomologi- 

 cal sense, is applied only to that succession of changes of 

 which such a definite pupal condition forms the middle term. 



It is obvious that a metamorphosis, in this sense, is a sec- 

 ondary complication superinduced upon the direct and grad- 

 ual process of development exhibited by such insects as the 

 Cockroach; 1 and that the Metabola, as insects having a 

 metamorphosis are termed, are, so far, more differentiated 

 than the Ametabola, or those which have no metamorphosis. 

 Again, in each of these divisions it is clear that the insects 

 w T hich never possess wings are less differentiated, or more 

 embryonic, than those which are winged. And, finally, insects 

 with the parts of the mouth in the condition of ordinary 

 gnathites are less differentiated than those in which such 



1 Sir John Lubbock has shown that the young Cliloeon (Ephemera) dimidi- 

 atum undergoes more than twenty ecdvse^, each accompanied by a slight 

 change of form in its passage to the adult state. (" Transactions of the Lm- 

 na?an Society," 1863.) 



16 



