



CONTENTS. 



CHATTER 1>AGE 



X. THE TRACHEAL SYSTEM OF THE IMAGO - 351 

 SKC. I. General Morphology and Development of the Tracheal 



System in Insects - - 351 



a. General Arrangement - - 351 



b. Development - 353 



c. Morphological Significance - - 355 

 SEC. 2. The Tracheal System of the Blow-Fly - - 358 



a. The Spiracles and Spiracular Sacs - - 358 



b. Structure of Tracheae and Air Sacs - - 364 

 SEC. 3. The Development of the Tracheal System in the Blow- 

 Fly - 368 



SEC. 4. The Physiology of Respiration in Insects - 373 



APPENDIX TO CHAPTER X. Calculation of Work done in Flight 387 



XI. THE ALIMENTARY CANAL OF THE IMAGO - 389 



SEC. i. The Mouth and Pharynx - - 390 



,, 2. The Soft Parts and Mechanism of the Proboscis - 390 



a. The Muscles of the Proboscis - 391 



b. The Oral Lobes and Structure of the Pseudo-tracheae 393 



c. The Mechanism by which the Proboscis is extended 



and erected - - 395 



d. Function of Oral Lobes - 397 



e. Nerves and End Organs - 402 



f. Salivary Glands - 404 

 SEC. 3. The (Esophagus, Stomachs and Intestines, and their 



Accessory Glands - - 407 



a. The Alimentary Tract- - 407 



b. The Malpighian Tubes - 412 



c. The Rectal Papillae - 417 



