348 THE SPINAL CORD. 



of the spinal nerves, nor help to form the longitudinal fiber-tracts 

 of the cord. Their axones arborize and end in the gray substance 

 of both crescents. Those axones of the Golgi cells which cross 

 over through the posterior commissure to the opposite crescent 

 help to constitute the "immediate decussation" of the pain and 

 temperature path. There are also Deiters cells in the head of the 

 posterior columna; their axones enter into the posterior fasciculus 

 proprius of the cord, hence they belong to the strand-variety. 

 They appear to form the ventral field of the posterior column 

 (Hoche) called the cornu-commissural tract, and at least a part 

 of the comma, oval and septo-marginal tract. The neurones 

 in the caput of the posterior columna receive posterior root-fibers 

 which carry excito-reflex impulses and impulses of the tactile, 

 pain and temperature senses. The former are transmitted for- 

 ward largely in the same crescent to the center and anterior columna ; 

 the latter, to a considerable extent, are carried through the pos- 

 terior commissure to the anterior columna of the opposite cres- 

 cent. 



Nucleus Dorsalis (Stillingi and Clarki). This column, which 

 was discovered by Stilling, is composed of cell-bodies measuring 

 from 40 fj. to 90 in diameter (Figs. 102 and 104). It forms a 

 most striking feature of the gray crescent throughout the thoracic 

 region. It is situated near the medial surface of the base of the 

 posterior columna, bounded laterally by a curved strand of pos- 

 terior root-fibers ; and forms a continuous column from the seventh 

 cervical segment to the second lumbar segment. The column 

 is largest in the lower two thoracic segments, where it bulges out 

 the medial surface of the posterior columna. It is represented 

 by separated groups of cell-bodies in the third and fourth sacral 

 and first three or four cervical segments of the cord and in the 

 accessory nucleus of the cuneate column in the medulla oblongata. 

 The limitation of the dorsal nucleus, as an unbroken column, 

 to the region of the white rami communicantes has suggested its 

 connection with the sympathetic system; and it is the terminal nu- 

 cleus of afferent sympathetic fibers, but it gives rise to no efferent fibers 

 of that system. All the axones of the dorsal nucleus appear to 

 run toward the lateral surface of the cord and enter into the cere- 



