No. I.] THE VERTEBRATE EAR. i^j 



ser dem finde ich noch, dass von der dorsalen Wand des Gan- 

 glion cochleare ein sehr diinnes Zweigchen abgeht, welches sich, 

 wie mir schien, nach der Wand des innerhalb des knorpeligen 

 Labyrinths verlaufenden Theiles des Ductus endolymphaticus 

 begiebt, spater abortirt dasselbe wieder." 



Kuhn's account of the innervation in adult Reptiles (Turtles 

 and Ophidia) agrees with the later embryological evidence given 

 by Hoffmann {cf. 172, 1882). 



Retzius has called attention to the fact that Breschet {loc. cit. 

 p. 89) had long ago (1833) correctly described the innervation 

 of the parts of the human ear. Of late years, however, anato- 

 mists have neglected Breschet's investigations and adopted the 

 erroneous statement that the three ampullas of the semicircular 

 canals are supplied by the vestibular {i.e. utricular) branch of 

 the auditory nerve. Retzius was led to renewed investigations 

 on this point by finding that all other vertebrates than the 

 Mammalia, although agreeing among themselves as to the in- 

 nervation of the parts of the internal ear, differed in this one 

 thing from the mammals. The results of his studies form 

 another contribution toward the demonstration of the intimate 

 genetic relationship of all vertebrates above Amphioxus. 



As we have just shown, the Ganoids, Dipnoids, Teleosts, Am- 

 phibia, and all the Reptilia and Birds agree in essential particu- 

 lars with the Elasmobranchs ; and many forms from the larger 

 groups, and several from each of the smaller groups, have 

 been accurately studied in this respect. The relations of the 

 parts in man and the Mammalia had long been in a confused 

 state. We now know, thanks to the painstaking and skilful 

 investigations of Retzius, that man forms no exception to the 

 general law governing the development of the ear in other 

 animals, and that he has no parts not represented in Elasmo- 

 branchs in some condition. The distinctive features of the 

 human ear as a type of the mammalian class is the great differ- 

 entiation of the cochlear region with the consequent distortion 

 and more complete separation of the parts of the canal complex. 

 It is with regret that one finds these misleading errors diligently 

 perpetuated in our text-books of science. In revising the chap- 

 ters on the nervous system for the fifth edition of his text-book 

 of Physiology, Foster has retained the erroneous account of the 

 innervation of the auditory organ, on which he bases certain 



