156 



NERVOUS SYSTEM OF VERTEBRATES. 



dorsal nerves of the trunk and head with the exception, in most 

 vertebrates, of the trigeminus and ophthalmicus profundus nerves. 

 In the trunk (Fig. 77) the fibers have their ganglion cells in the 

 spinal ganglia and go by way of the white rami communicantes 

 through one of the ganglia of the sympathetic chain, and by way 



FIG. 78. A transverse section through the region of Clarke's column of the 

 thoracic cord of a new-born dog. FromCajal (Textura, etc.). A, Clarke's column; 

 B, ending of collaterals in it; C, collaterals ending in the intermediate nucleus; 

 D, reflex-motor collaterals; E, ventral commissure; F, middle commissure; G, dor- 

 sal commissure; H, cells of the dorsal commissure. 



of sympathetic nerves to some of the organs of the viscera. In 

 the spinal cord these fibers have their central endings in a part 

 of the gray matter lying at the base of the dorsal horn, known 

 as Clarke's column, and perhaps in connection with other cells 



