Turner, Morphology of tJie Avian Brain. 275 



neal preparations, these cells are densely stained, and each 

 one presents a densely stained nucleus, within which is a 

 densely stained nucleolus. This nidulus is well supplied 

 with Deiter's corpuscles. 



Xidulus of the Hypoglossal Nerve (Plate XVIII, Fig. 17). 

 — Further ventrad, and separated from the nidulus of the 

 spinal accessory by a cell-less region, lies the large nidulus 

 of the hypoglossal nerve. This nidulus is sub-pyramidal in 

 shape. Its base is about at the junction of the myelon with 

 the metencephalon, while its apex is as far cephalad as the 

 caudad extremity of the nidulus of the glosso-pharyngeal 

 nerve. 



This nidulus is composed of large pyramidal cells, which 

 resemble those of the nidulus of the spinal accessory nerve. 

 In haematoxylin and in aluminium- sulphate cochineal prepa- 

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

 a densely stained nucleus, within which is a densely stained 

 nucleolus. This nidulus is vs^ell supplied with Deiter's 

 corpuscles. 



Olives. — Near the ventral surface of the metencephalon, 

 and immediately laterad of the root of the hypoglossal nerve, 

 there is a small, ill-defined cluster of cells. This nidulus is 

 probably the homologue of the olivary body. However, this 

 nidulus does not exhibit the slightest trace of the complex 

 structure of the human olivary body.(') The cells of this 

 nidulus are small. In ha^matoxylin and in aluminivim-sulphate 

 cochineal preparations, the nuclei of these cells are much 

 more densely stained than is usually the case in flask cells. 



Accessory Olives (Plate XVIII, Fig. 13). — Near the ven- 

 tral surface of the metencephalon of a young dove ( Coluniba 

 livia) a small, ill-defined cell cluster has been observed. It 

 is composed of fusiform cells, and is probably a homologue 

 of the accessory olives. In haematoxylin preparations these 

 cells are faintly stained, and each one presents a large, clear 



I See Rannev, op. cit., p. 268 and p. 262, Fig, 59. 



