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NORMAL HISTOLOGY AND ORGANOGRAPHY. 



distributed and some of them are particularly small 

 and have a stellate appearance. At the base and 

 mesial surface of this horn there is a group of large 

 nerve cells called the column of Clarke. This column 

 extends from the second lumbar up through the 

 dorsal region of the cord to the cervical. In the 

 cervical region it is absent; however, Stilling' s nu- 

 cleus of this region may represent a remnant of the 

 column of Clarke. At the base of the dorsal horn, 

 deeper down and lateral to Clarke's column, another 

 group of nerve cells may be found that is called 

 Waldeyer's central cell column. This is reciprocal 

 with Clarke's column; that is, in the dorsal region 

 where Clarke's column is conspicuous, only rem- 

 nants of Waldeyer's tract can be found, while in the 

 other regions of the cord this cell tract is particu- 

 larly prominent. 



The lateral horn is a small lateral prominence at 

 the side of the gray crescent. In the substance of 

 this, a small collection of nerve cells may be found, 

 while just beneath this the gray matter cuts into 

 the white matter, forming processes called the 

 processus reticularis. 



The anterior horn is not only large but presents a 

 blunt, rounded appearance. The nerve cells of this 

 horn are very large and have been classified according 

 to their position into antero-mesial, postero-mesial, 

 antero-lateral, and postero-lateral. The axis cylin- 

 der of most of these cell bodies goes to form the an- 

 terior root of the spinal nerves. They therefore 

 carry only motor impulses. 



White Matter of the Cord. The white matter of 



