I lO ELEMENTARY BIOLOGY. [CHAP. 



S. The recurrent laryngeal ; a long nerve arising in 

 front of and above a — y and coursing round the 

 base of the puhnonary aortic arch to reach the 

 larynx. 



<. The dorsal ramus ; arising from the main trunk 

 immediately after it leaves the skull, and dis- 

 tributed to the adjacent dorsal integument. 



<r. Incidental. 



a. The course of the 5th and 7th (cf. § 4. ii. d. e. 

 et seq.). Remove the eye and the squamosal 

 and quadrato-jugal bones and follow tlie course 

 of the above nerves, as seen from the side. 



Note especially the relations of the 5th to the 

 mouth-cavity and of the 7 th to the tympano- 

 Eustachian passage (Eustachian recess). See 

 pp. 28, 29. 



p. The synipatheiic. Note especially the further 

 course of the splancJinic 7ierve (§ 5. /?). It 

 bears a large ganglion in close proximity with 

 the coeliaco-mesenteric artery; add a little acetic 

 acid ; offshoots will be found to proceed from it 

 to the alimentary canal, accompanying, at their 

 outset, the branches of the artery. 



J^ The anatomy of the sense organs. 



I. The gustatory organ. 



The shape and arrangement of the tongue have 

 already been described (Sect. E. § i d.). Snip o(T a 

 bit of mucous membrane from the upper surface of 

 the tongue of a recently killed frog, mount in salt 

 solution and cover in plenty of the fluid with a large 

 covcrslip : examine with one inch obj. 



