182 HOW TO KEEP BEES 



This arrangement of parts holds with the append- 

 ages of the body of an insect as well as with the body 

 itself; the legs, mouth-parts and antennae are all 

 tubular organs, having a firm outer skeleton support- 

 ing the inner parts. 



Movement of the body and its appendages is 

 provided for by narrow, flexible, zone-like areas in 

 the skeleton which encircle the body and the ap- 

 pendages, at frequent intervals. This segmented 

 condition of the body is easily seen in the hind part 

 or abdomen, which appears to consist of a series of 

 rings. 



The microscopic structure of the body-wall is 

 comparatively simple. There is an inner cellular 

 part which consists of a single layer of cells: this is 

 the hypodermis (Plate XXV, 2, h) ; and the outer or 

 hard part: this is the cuticle (Plate XXV, 2, c). 



The hypodermis is the active living part; it pro- 

 duces the cuticle, which receives additions from 

 it constantly during the life of the insect. On 

 this account, when a section of the cuticle is 

 examined with a microscope it presents a layered 

 appearance. 



Moulting of the cuticle. — ^From time to time during 

 the growth of the insect the outer layers of the 

 cuticle are shed; this is known as moulting. After 

 a moult, the inner layers of the cuticle, which have 

 now become the outer layers, but w^hich are still 

 soft, stretch to accommodate the increased size of 

 the body, and then soon become hard. This moult- 

 ing, or shedding of the skin, takes place about six 



