Literary Notices. clxix 



of special sense, existing fully developed in the lower forms of animal 

 life than to endings upon sensory epithelium. 



The silver method shows that the pituitary gland has retained in 

 one of the higher orders of vertebrates (adult dogs) its double role of 

 secretory and nervous function intact; the former perhaps modified, 

 the latter, the original special sense organ, probably simply lying quies- 

 cent, not atrophied, and only changed so far as to admit of a slightly 

 different arrangement of its constituent elements. 



The Brain of Birds. 1 



The earlier parts of this work previously abstracted (Vol. Ill, 

 pp. cxii-cxvii) dealt with the transition between the cord and the med- 

 ulla and the internal origins of the nerves from the medulla. The 

 Hypoglossus (I) and the the Vagus groups (II) were discussed. 



III. Acusticus Group, (a). Nervus cochlearis. This nerve 

 springs from a ganglion which contains three structurally distinct ele- 

 ments which probably not only constituted originally a single ganglion 

 but one which was gradually imbedded in the substance of the med- 

 ulla from without. Not all of the emerging fibres spring from cells of 

 this cluster and on the other hand the cells of the most ectal [division 

 contribute fibres to the corpus restiforme as well as the cochlear root. 

 Those fibres of the cochlearis which pass further cephalad first enter 

 the raphe in which they pass forward and occasionally cross. These 

 are assumed to be the central tract of the acusticus, while other 

 smaller fibres at first associated with them, which cross immediately 

 in the raphe, pass to the formatio reticularis and thence to the cere- 

 bellar peduncle. The cochlearis also probably gives a tract to the 

 cerebellar peduncle of the same side. The passerine birds have the 

 ganglia of origin of the cochlearis more extensively and more intric- 

 ately developed than any others except the owl, in which the ganglia 

 are larger. 



(b). Nervus vestibularis. The greater part of these fibres pass 

 directly to the raphe. It is interesting to note that, like^' motor tracts, 

 they become medullated very early in new born birds. They origin- 

 ate in a root-ganglion external to the medulla but closely appressed to 

 it. After crossing in the raphe they seem to enter the dorso-median 

 fasciculus, an appearance which was confirmed by Marchi's method of 



1 Brandis, F. Untersuchungen ilber das Gehirn der Vogel. II Theil: 

 Ursprung der Nerven der Medulla oblongata (Continued); Das Kleinhirn. 

 Arch. f. mik. Anat., XLIII, I and 4, 1894. 



