6 INSECT TRANSFORMATION 



group or Phylum 1 of the animal kingdom to which not insects 

 only, but also shrimps and crabs, spiders and scorpions, 

 centipedes and millipedes belong. This cuticle is not a hardened 

 skin, consisting of transformed cells, once living units of the 





FIG. i. MIGRATORY LOCUST (Pachytylus migratorius). 

 A, dorsal view with wings extended; B, side view with wings folded. 

 Natural size. From Shipley and MacBride, "Zoology". 



creature's growing tissue. It is a lifeless envelope built up (or 

 secreted) by the skin which remains as a living sheet of cells 

 beneath it ; its chief constituent is a horny substance known 

 as chitin (Fig. 2). Being a secreted cuticle and not a living skin 



1 Indicating a race of creatures believed to be linked together by 

 community of descent. 



