TABLE OF CONTENTS 



b. The fore-intestine , 109 



The layers of the fore-intestine 109 



The intima 109 



The epithelium 109 



The basement membrane 109 



The longitudinal muscles 109 



The circular muscles 109 



The peritoneal membrane 109 



The regions of the fore-intestine 109 



The pharynx v 109 



The oesophagus no 



The crop no 



The proventriculus no 



The cesophageal valve in 



c. The mid-intestine in 



The layers of the mid-intestine in 



The epithelium 112 



Theperitrophic membrane 112 



d. The hind-intestine 112 



The layers of the hind-intestine ..."... 112 



The regions of the hind-intestine 113 



The Malpighian vessels 113 



The Malpighian vessels as silk-glands 113 



The caecum 113 



The anus 113 



4. THE RESPIRATORY SYSTEM 113 



a. The open or holopneustic type of respiratory organs 114 



1. The spiracles 114 



The position of the spiracles 114 



The number of spiracles 114 



Terms indicating the distribution of the spiracles 115 



The structure of spiracles 116 



The closing apparatus of the tracheae 116 



2. The trochees 1 16 



The structure of the tracheae , 117 



j. The tracheoles 1 18 



4. The air-sacs 1 1 8 



5. Modifications of the open type of respiratory organs 1 19 



b. The closed or apneustic type of respiratory organs 119 



J. The Tracheal gills 119 



2. Respiration of parasites 120 



j. The blood-gills 120 



