Development of the Xotochord 253 



child is formed by the liquefaction of the central portion of the con- 

 nective tissue of the intervertebral disc. He also described a tumor 

 found upon the inner surface of the base of the skull, and, believing 

 it to be a growth of cartilage, named it Ecchondrosis physalifora. 



Luschka, in 1856, adopting in part Virchow's theory of the origin 

 of the nucleus pulposus, found that its characteristic tissue,- which 

 consists of whitish clusters of vacuolated cells in a transparent gela- 

 tinous matrix, arises primarily by the liquefaction of the intervertebral 

 notochord expansion, but that it is augmented by the liquefaction of the 

 surrounding fibro-cartilage. He also accepted Virchow's theory of the 

 nature of Eccliondrosis physalifora. 



Two years later, 1858, Luschka published the second edition of his 

 '"Plalbgelenke," in which he described the nucleus pulposus at various 

 ages. He found further evidence of the close relationship of notochor- . 

 dal tissue and cartilage. The sharp boundary line between the noto- 

 chord and the intervertebral disc which occurs in the new-born child, 

 owing to the formation of papillae of fibro-cartilage which project into 

 the notochordal tissue, disappears during childhood. liiquef action finally 

 leads to the obliteration of the boundary between the two tissues. In 

 old age the nucleus pulposus becomes of dirty green or gray color. It 

 loses its gelatinous and elastic character while cheesy masses, the 

 products of fatty degeneration, as well as calcareous, masses, appear in 

 it. A large number of cartilage cells with thick, strongly laminated 

 walls are found in it. Some of these are iirunense mother cells with 

 innumerable daughter cells. Fat vacuoles are visible in many cells. 



In the same year Heinrich Miiller noted that portions of the noto- 

 chord persist for a long time after birth in the base of the skull, in the 

 odontoid process of the axis and in the coccyx. He tried to demon- 

 strate that Eccliondrosis physalifora is produced by excessive growth of 

 notochordal tissue. 



Kolliker says in the fifth edition of his "Histology:" — "In 1858 

 I pointed out that the intervertebral ligament of a child of one year 

 contains ordinarily a pear-shaped cavity which is filled with the continu- 

 ously growing mass of the notochord ; and that this mass, which consists 

 of a soft matrix and many cells with characteristic vacuoles arranged 

 in clusters or in a network of strands, forms in the adult a 

 large part of the nucleus pulposus in which, in certain cases, the char- 

 acteristic fcetal notochordal cells can be recognized. . . . This soft 

 mass" (of fibro-cartilage, which Kolliker regards as the peripheral 



