INTERNAL STRUCTURE OF THE GRASSHOPPER. 267 



pass out into tubular spaces in the tympanum, where they 

 terminate in small expansions, which appear to be the 

 parts of the apparatus which are directly affected by the 

 vibrations of the membrane. The microscopic structure 

 of the larger ganglion (m) has been investigated (Ranke, 

 Zeit. f. Wiss. Zool. xxxv. 1875, p. 143) in the genus 

 Acridium. 



Fia. 141. Auditory ganglion of 

 Acridium cerulescens, greatly magnified, 

 after Ranke (Beitrage zu der Lehre von 

 den Uebergangs-Sinnesorganen, Zeit. Z. 

 Wiss. Zool. xxv. 1875, p. 143). 



B. The auditory nerve and ganglion. 

 a. External or peripheral face of the 

 ganglion. &. Transparent portion. 



c. Pigmented portion. d. Auditory 

 nerve, e. Fusiform bodies. /. Their 

 stems, g. Layer of nuclei, h. Gan- c 

 glion cells. A. Termination of a nerve 

 fibre, very highly magnified, a. Fusi- 

 form body. b. Stem. c. Nucleus. 



d. Fibre which connects it to the gan- 

 glion cell, e, f. Nerve fibre. 



12. According to this author, when the fresh ganglion 

 is removed with needles from the surface of the tympanum 

 of a grasshopper which has just been killed, and is placed 

 in water on a slide and examined with a high power of the 

 microscope, it is seen to be a' bell-shaped structure (Fig. 

 141, B), in which are seen : 



a. The flattened peripheral surface (a), which normally 

 lies in contact with theside of the cone-shaped promi- 

 nence (Fig. 140, e). 



b. The opposite rounded end. 



c. The auditory nerve (d, Fig. 141), in which are to be 

 seen : 



