David Sharp and George Herbert Carpenter, 1911 Encyclopædia Britannica, Volume 13… (1911)
“ The outer cellular layer (ectoderm or “hypodermis”) of insects as of other Arthropods, secretes a chitinous cuticle which has to be periodically shed and renewed during the growth of the animal. The regions of this cuticle have a markedly segmental arrangement, and the definite hardened pieces (sclerites) of the exoskeleton are in close contact with one another along linear sutures, or are united by regions of the cuticle which are less chitinous and more membranous, so as to permit freedom of movement. ”
