THE EAR OF MAN. 



197 



o-iven off from the ampullar branch to an abortive 

 ampullar organ for which Retzius proposed the name 

 of macula neglecta. In the figure of the Torpedo ear 

 this organ would lie in the ampullar tube of the 

 posterior canal about where the horizontal canal crosses 

 it, and its nerve would be in the figure entirely hidden 

 from view. 



Both Hasse and Retzius, after many years spent in 

 the comparative study of the internal ear, have decided 

 that between the ears of the Cyclostomata and the ver- 

 tebrates of the gnathostome type there was no discern- 



FlG. 2. — The right internal ear of the Hag- 

 fish {Myxine glutinosa)^ seen from the inside 

 or cerebral face. Figure after G. Retzius. The 

 figure represents the ear somewhat enlarged, 

 and does not show the shape or exact positions 

 of the contained sense-organs. 



mu,. 



a Anterior ampulla. 



ap Posterior ampulla. 



c Anterior and posterior canals. 



^": I Ampullar ends of the same. 



d Ductus endolymphaticus. 



ifi7i Macula utriculi et sacculi. 



n Nerve branchlets. 



u Utriculo-sacculus. 



J Sacculus endolymphaticus. 



ible basis of homology. The gulf separating the two 

 types prevented the recognition of such genetic rela- 

 tionships as might exist. Since my studies lead to a 

 very different conclusion, a short account of the salient 

 features of the Cyclostome ear, introduced here, may 

 serve as a preliminary to the consideration of the mor- 

 phological laws governing the development of the ver- 

 tebrate ear, alike in its ontogeny and its phylogeny. 



The internal ear of Myxine (Fig. 2) is the simplest 

 known among vertebrates. It is divided by a vertical 

 line passing through the letter c, the sac of the endo- 



