630 'Journal of Comparative Neurology and Psychology. 



ventral horn of the cord or in the ventral area of the medulla, and 

 the visceral efferent nuclei lie in the lateral horn of the cord and 

 are continued into the medulla as the lateral column of gray matter, 

 subdivided in higher vertebrates into two minor columns, repre- 

 sented by the nucleus ambiguus and the dorsal vagal and glosso- 

 pharyngeal nuclei. Johnston ascribes to the visceral motor 

 fibers the control of "the smooth muscles in the viscera and else- 

 where in the body, the muscles of the heart and blood vessels, cer- 



mm:''" 



Wm 



X 



1^,^ XI ^^^ ij^s^ 



Fig. 7. Human embrj'o, 29.0 mm. (H. E. C. series 914, section 419) camera drawing. X 85. 

 The section passes through the vagus, accessory, and hypoglossal nerves at their junction. X.g., jugular 

 ganglion of vagus; v. jug., jugular vein, into the wall of which passes a branch, a, of the hypoglossal 

 nerve, with same direction as a dorsal ramus. 



Fig. 8. Copied from Corning (1899.2), Taf. iv, 12. Forelimb of Lacerta viridis. coe., coelom; 

 / /., limb hud; d.L, dorsolateral; v.m., ventro-mesial cells of the myotome; v.L, ventro-lateral cells, form- 

 ing muscle bud of limb. X 100. 



tain striated muscles derived from lateral mesoderm, and the 

 glands of the body;" while the somatic motor fibers control directly 

 "the actions of the typical body muscles; namely, those derived 

 from the dorsal mesoderm or somites." In the cord of verte- 

 brates both of these components run in the ventral root, but in the 

 cord of some lower forms, and in the medulla and pons of verte- 

 brates the somatic motor component alone runs as a ventral root; 

 the visceral motor component becomes a lateral root. This means 



