15 
CHAPTER III. 
EXTERNAL SKELETON. 
Structure — Chituie — Hypodermis and Epidermis — Hairs and 
their Uses — Hairless Bees — Division into Three Barts. 
The honey bee, like all other insects, has neither 
bones nor cartilaginous framework. The external 
covering is formed of a tough and leathery skin, which 
looks like horn, but is very different from it in its 
composition. This substance is called chitine. It 
is not acted upon by ordinary solvents, such as water, 
alcohol, ether, or diluted acids, and differs from horn, 
which dissolves readily in a weak solution of potash. 
The thick and the thin outer skins, whether they 
form the rings, wings, hairs, eyes, or joints which are 
pliable and easily folded, are composed of this same 
substance. The skin is formed of two layers — an 
inner one, called the hypodermis., or true skin, soft and 
not made up of chitine ; and the outer one, called 
epidermis, composed of chitine, to which are added, 
according to the stages of development of the insect, 
more or less colouring matter, fat, and calcareous 
salts. It is this outer skin which is detached and cast 
during the progress of development, and not only 
forms the hard external skeleton, but also the internal 
braces, tendons, and membranes. 
Every part of the epidermis is covered more or 
