CONTENTS. v 



CHAPTER PAGE 



SEC. 9. On the Structure and Functions of the Antennae - 582 



a. General Considerations - 582 



b. In the Blow-Fly Imago - 585 



c. On the Functions of the Antenna; in Insects generally 589 

 SEC. 10. Auditory and Sound-producing Mechanisms- - 595 



a. Chordotonal Organs - 595 



b. Tympanic Organs - - 599 

 SEC. ii. The Halteres of the Blow-Fly - - 603 



a. General Structure and Morphology - 603 



b. Special Sensory Structures- - 609 



c. On the Functions of the Halteres - - 614 

 SEC. 12. The Wing Organs - 620 



13. The Tympanic Organs of the Blow-Fly - 623 



a. Structure of Tympanic Organs - 623 



b. On the Probable Function of the Tympanic Organs 



and their Relation to the Halteres - 626 



SEC. 14. Concluding Remarks on the Phenomena of Hearing 



in Insects - - 629 



SEC. 15. The Sense of Taste and the Gustatory Organs - 630 



1 6. The Prosternal Organ- - 633 



XIV. THE CIRCULATION OF THE BLOOD AND THE DORSAL VESSEL 635 



SEC. i. The Circulation in Insects generally - - 635 



2. The Dorsal Vessel of the Imago of the Blow-Fly - 639 



3. The Physiology of the Dorsal Vessel - - 650 



4. The Development of the Dorsal Vessel - 656 



XV. THE GENERATIVE ORGANS - 658 



SEC. i. Descriptive Anatomy of the Internal Generative 



Organs of the Male Blow-Fly - - 660 



2. Descriptive Anatomy of the Internal Generative 



Organs of the Female Blow-Fly- - 666 



., 3. The Structure of the Egg in the Blow-Fly - 678 



,, 4. On the Development of the Internal Generative Organs 684 



a. The Earliest Appearance of the Gonads in the 



Embryo and Larva - 684 



b. On the Supposed Origin of the Rudimentary 



Gonads in the Embryo from the Polar Cells of 

 Weismann - 689 



c. The Development of the Testes and their Ducts, 



and of the Paragonia in the Blow-Fly - - 691 



d. Spermatogenesis - 692 



