638 journal of Comparative Neurology and Psychology. 



innervates the muscles derived from the lateral mesoderm the 

 pharyngeal, laryngeal, oral and facial muscles: it also supplies the 

 vaso-motor and excito-glandular fibers to the sympathetic ganglia 

 of the head. This component appears again in the oculomotor 

 nerve, supplying the ciliary ganglion with vaso-motor fibers, and 

 probably innervating the smooth muscles of the eye; but this 

 latter statement is mere conjecture, as the origin of these muscles 

 is not understood. Here the component has resumed its original 

 course taken in the cord, and issues by a ventral root; this is 

 accounted for by the fact that at this level the sides of the brain 

 are no longer opened, as in the medulla, so that the ventral root 

 is the shorter course. Either the Edinger-Westphal nucleus, 

 which has been supposed to be the center for pupillary reflexes 

 (though this is denied by Tsuchida (1906.1), or the nucleus of 

 Darkschewitsch, which is described as a lateral group of cells, 

 probably represents the dorso-lateral nucleus of this visceral 

 efferent component. 



CONCLUSIONS. 



In a large percentage of human embryos there are found fibers 

 continuing the line of ventral roots between the hypoglossal nerve 

 and the abducens. Some of these have a ventral course, like the 

 hypoglossal roots, others have a lateral course, like the dorsal rami 

 of spinal nerves. Of each kind some pass behind the vagus and 

 accessory trunk, some between the vagus and the glossopharyngeal 

 nerves. Those in front of the vagus probably represent a ventral 

 root of the glossopharyngeal nerve. 



It is suggested that there are three motor components in a typical 

 nerve, arising in three groups of cells in the ventral horn, or in 

 corresponding parts of the medulla, pons, and mid-brain: (i) 

 the ventro-mesial, running to the ventral body muscles: (2) the 

 ventro-lateral, innervating the muscles of the back and of the 

 limbs, which are here considered homologous muscles; and (3) 

 the dorso-lateral, or visceral efferent, supplying the vaso-motor 

 and excito-glandular fibers, and also innervating the muscles 

 derived from lateral mesoderm : i.e., the smooth muscles of the body 

 and the striated muscles of the face, pharynx and larynx. 



The ventral mesial components always leave the cord or brain 

 by ventral roots; the ventro-lateral and dorso-lateral components 



