90 Journal of Comparative Neurology. 



cord (afferent sympathetic center); fibers constitut- 

 ing the sensory VII, IX, and X roots exclusive of 

 components above mentioned and (2) below, and 

 reaching their final distribution by way of the vis- 

 ceral rami of the cranial nerves : innervating the 

 general mucous surfaces. This sub-division in all 

 vertebrates mediates only the vague "general" or 

 "organic" feelings and seldom or never gives rise 

 to immediate reflexes directed toward the envir- 

 onment. 

 2. End-bud sub-division : center and fibers not as yet 

 distinguishable from those of (i); innervating taste 

 buds in the mouth and end-buds in the branchial 

 cavities and over the surface of the head and body. 

 This sub-division serves especially the gustatory 

 function, including testing the water with refer- 

 ence to its fitness for respiration. It gives rise to 

 / reflex movements of the visceral (lateral plate) 



musculature. 

 B. Efferent (motor, secretor}') divisions. 



a. Somatic motor : brain centers corresponding to the 



ventral horn of the cord ; fibers constituting the 

 motor III, IV, VI, and XII nerves ; innervating 

 somatic musculature (from the mesoblastic somites), 



b. Splanchnic motor : brain center corresponding to the 



lateral horn of the cord ; fibers constituting the 

 motor V, VII, IX, and X nerves ; innervating mus- 

 cles of the branchial, hyoid, mandibular, and labial 

 cartilage arches (derived from the lateral plates). 

 Thus the nervous system is analyzed into four great divis- 

 ions, of which it may be said in general that the somatic sensory 

 and somatic motor divisions act together in the external, animal 

 activities of the organism ; while the splanchnic sensory and 

 motor divisions have to do with the internal and vegetative ac- 

 tivities. The somatic divisions have to do with external, spe- 

 cific, localized, conscious sensations and with reflex or volun- 

 tary, conscious, movements in relation to external environment; 



