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 which 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 



