116 THE ELEMENTARY NERVOUS SYSTEM 



In 1855 Leydig discovered in the ganglionic bodies of 

 spiders what appeared to be a finely granular material 

 which he called punctate substance. Similar material 

 was also shown to be a considerable constituent of the 

 gray matter of the vertebrate nervous system. Hence, in 

 addition to nerve fibers and nerve cells, a third kind of 

 material was shown to be present in many nervous or- 

 gans. This material, as was subsequently demonstrated 

 in 1871 by Gerlach, consisted in reality of very fine fibrils 

 which when seen in section appeared as minute points and 

 hence Leydig 's name for it of punctate substance. 



The uncertainty of the relation of this fibrillar ma- 

 terial to nerve fibers and to nerve cells was not removed 

 until the Golgi method of silver impregnation began to 

 be generally applied to nervous tissues. This method 

 yielded such important results that in May, 1891, K61- 

 liker could substantiate the claim that every nerve fiber 

 in the body was at some part of its course directly con- 

 nected with a ganglion cell, and in June of the same year 

 Waldeyer, on the basis of conclusions drawn largely from 

 Golgi preparations, promulgated the theory of the neu- 

 rone, the first consistent account of the nerve cell. Ac- 

 cording to this well-known doctrine the ganglion cell of 

 the older workers is really the nucleated body of the true 

 nerve cell, or neurone, whose processes are commonly of 

 two kinds : fine protoplasmic processes from the cell body 

 and nerve fibers with their final branchings. Both these 

 kinds of processes may contribute to the formation of the 

 finely fibrillar material already noted. This material was 

 believed to be the means of intercommunication between 



neurones. 



The embryological investigations of His (1886) and 

 other workers showed that the embryonic nerve cells, or 



