CONTENTS. vii 
CuaptTEer IV.—ANATOMY AND PHYSIOLOGY. 
THORAX : Page 
Second division of the insect body .. -.. 88 
Relation of its skeleton to the larval segments ee oe 
Prothorax, its subdivisions a ae : 90 
Mesothoraz, is és és +s és ‘ 91 
Its sternal aspect se ‘s es os es ss «6-81 
Metathoraz, its subdivisions .. aX we ss ‘ 92 
Muscles of the thorax, voluntary ‘ed involuntary ‘ | 
Their general structure .. 7 *e : . os 95 
And arrangement Pent dws ae 4s ir « 96 
Muscles of flight .. in wd = a os 97 
Their respiratory function oe eis - ee . 98 
Salivary glands, their position ..° .. - : oe ‘99 
Structure and functions .. ¢s o- . “> -- 100 
THORACIC APPENDAGES. 
Les, their general structure we , ; ve 108 
Tarsi of wasp and honey-bee compared. ‘ : -- 104 
Feet, structure of. . os és es 105 
WinGs, arrangement of the nervures.. “e -. 106 
Structure of the wings .. «e on : oe +» 108 
Hooklets and locking-gear in wasps... ‘ oP «» 109 
In other insects .. ots oe vie ‘ oe sein LO 
Direction of the movements of the isi vie ; 112 
Mechanism of flight. . ~e oe ° : cory aD 
Requisites of a Selatan. as es ‘ 7 -- 114 
Elements of the problem of flight .. on os e4 ee 
Passive : 
Ratio of area of wings to weight .. : ‘ « 6 
Influence of form and position oe a ee Pen bY 
Active : 
General principles of aérial propulsion se , «- 118 
Upward pressure in horizontal flight - ee -- 119 
Direction of the blow of the wings v6 ne ov) 119 
Strength required for flight .. os “a o se) 128 
CuapteR V.—ANATOMY AND PHYSIOLOGY 
ABDOMEN : 
Third division of the insect body de a os 125 
Its external figure ee ee ou ‘ ‘ «» 125 
