665 



and the poor development of the nucleus ambiguus in its spinal third 

 part in Camelidae. If this be so, one might conclude, judging from the 

 strong development of the nucleus at this place in the giraffe, that tiic 

 nervus recurrens, even in this animal in spite of its long neck, well 

 deserves its name, in which case the highly exceplional condi- 

 tions of this nerve in Camelidae have wrongly been connected by 

 Lesbre with the unusually long neck of these animals. 



As regards the conditions of the nucleus accessorii in the giraffe 

 I wish to make the following observation. No agreement exists yet 

 as to the position, extent and nature of this nucleus. Most observers 

 are agreed upon the position of it in the first cervical segment, 

 viz. about the level of its leaving the nervus accessorius, on the 

 border of the anterior and posterior horns and their neighbourhood, 

 or, according to the nomenclature of Waldeyer, in the lateral 

 portion of the. middle horn. This position has already been fixed by 

 Clarke. Roller and Darkewitsch beliexed that here also the XI 

 nucleus was situated in the most ventro-Iateral portion of the frontal 

 horn. According to Dkes only the most dorsal of the 'cells of this 

 group belong to the cells of the accessorius nucleus, while only 

 anterior horn roots arise in the venti'al. He pointed out that in the 

 cranial part of the first cervical segment the XI nucleus shifts 

 to the anterior horn and then comes to lie sideways: Kaiser too 

 indicates that spinally from the first cervical segment the XI 

 nucleus shifts distally. According to Obersteiner the said nucleus 

 lies first (5"' cervical segment) dorso-lateral in the anterior horn, 

 near its border ; in a cerebral direction, however, it shifts cen- 

 trally, to pass over into the nucleus ambiguus. Cajal indicates as 

 the position of the XI nucleus, as regards the spinal portion, the 

 lateral edge of the frontal horn, and more frontall'y the whole dorsal half 

 of that. Kappers, found the nucleus on a frontal level, dorso-lateral from 

 the canalis centralis, spinally more latero-ventral towards the border of 

 anterior and posterior horns and finally latero-ventral tVom it. Langelaan 

 also desci'ibes the nucleus in the dorso-lateral poition of the front 

 horn, and from the illustration it a{)pears that here too the boundary 

 between the anterior and posterior horns is meant. Jacobsohn and 

 Walter assume ascending cells from the medial group of frontal horn 

 cells to the nucleus accessorii; Ziehen states that the nucleus in 

 question, in the 1>*' cervical segment is formed by a pyramidal 

 protrusion of the gray matter radiating at the base of the anterior horn 

 into the substantia reticularis, which protrusion he names processus 

 postero-lateralis coriiu auterioris, and which he regards as a direct 

 continuation of the dorso-lateral group of frontal horn cells. 



43* 



