370 JOURNAL OK Comparative Neurology. 



aggregated, and among them is dirtributed a large number of 

 Deiter's corpuscles, 



Deep Motor Xidulus of the Fifth Nerve (Plate XVIII, 

 Fig. 16). — Near the meson, on a level with the niduli of the 

 glosso- pharyngeal and pneumogastric nerves and extending 

 as far cephalad as the roots of the trigeminal nerve, there 

 exists an elongated sub-ellipsoidal nidulus. This small cell 

 cluster lies immediately cephalad of the mesal extremity 

 of the deep motor root of the fifth nerve, and has its major 

 axis approximately parallel to the longitudinal axis of the 

 metencephalon. 



The nidulus is composed of a loose aggregate of large 

 pyramidal cells, among vv^hich numerous Deiter's corpuscles 

 are distributed. The apex of each cell is prolonged into a 

 long process, while the base is supplied with several shorter 

 processes. The apical process is often curved. In haema- 

 toxylon and in aluminium-sulphate cochineal preparations, 

 these cells are densely stained, and each one presents a 

 densely stained nucleus and a densely stained nucleolus. 

 Several small fasciculi of nerve fibres pass from this nidulus 

 to the raphe. 



In the avian brain there does not appear to be any homo- 

 logue of what in the human medulla(') is known as the 

 inferior sensory root of the trigeminus. 



Gasserian Ganglion (Plate XVIII, Figs. S, 15, 19). — This 

 is a large ganglion which is situated upon the root of the 

 trigeminal nerve. This ganglion consists of large typical 

 bipolar cells, which are arranged with their longitudinal axes 

 perpendicular to the metencephalon. In addition to the 

 ordinary cell wall, each of these cells is surrounded by an 

 additional sheath. In this sheath several nuclei are visible. 

 In haematoxylin and in aluminium -sulphate cochineal prepa- 

 rations, these cells are densely stained, and each one presents 

 a faintly stained spherical nucleus, within which is a 



I Ambrose L. Rannev, " The Applied Anatomy of the Nervous System,^' second 

 edition, p. 254, Figs. 55, 5. 



