CONTENTS. Vv 
CHAPTER PAGE 
SEc. 9. On the Structure and Functions of the Antennz - 582 
a. General Considerations - - - - 582 
4. In the Blow-Fly Imago - - - - 585 
c. On the Functions of the Antenne in Insects generally 589 
SEC. to, Auditory and Sound-producing Mechanisms - - 595 
a. Chordotonal Organs - - - - 595 
6. Tympanic Organs - - - - - 599 
Sec. 11. The Halteres of the Blow-Fly - - - - 603 
a, General Structure and Morphology - - 603 
6. 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 
6. On the Probable Function of the Tympanic Organs 
and their Relation to the Halteres - - 626 
Src. 14. Concluding Remarks on the Phenomena of Hearing 
in Insects - - - - - - 629 
Src. 15. The Sense of Taste and the Gustatory Organs - 630 
» 16. The Prosternal Organ - - - - - 633 
XIV. THE CIRCULATION OF THE BLOOD AND THE DORSAL VESSEL 635 
Sec, 1. 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 
SeEc, 1. 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. Onthe Development of the Internal Generative Organs 684. 
a. The Earliest Appearance of the Gonads in the 
Embryo and Larva - - - 684 
6, On the Supposed Origin of the sale aieeentti 
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 
da. Spermatogenesis - : : - 692 
