314 SPECIAL HISTOLOGY. 



from above to below. They are, however, invariably oblique, 

 so that those of the different layers cross each other. 

 Besides which, it must be remarked, that the individual 

 layers themselves also exhibit a more or less distinctly 

 foliated structure, constituted in such a manner that the 

 fine lamellae, in the portions composed of connective tissue, 

 observe the same direction as the layers themselves, whilst 

 in the fibro-cartilaginous portions they are disposed more 

 in the direction of the radius of the ligamentous disc. 



The softer central substance of the intervertebral liga- 

 ments, or the gelatinous nucleus of authors, does not differ, 

 essentially, from the portions above described ; for, even in 

 this situation, layers of connective tissue occur, although they 

 gradually diminish in proportion to the fibro-cartilage, and are 

 less distinctly defined. The nearer we approach the centre, 

 the less evident is any trace of an alternation of different 

 layers, and of a concentric arrangement of them ; the whole 

 becomes transparent, soft, and, finally, almost homogeneous. 

 The microscope shows the predominance of fibro-cartilage, with 

 large cells (0 - 012 — 0'02-i'"), frequently one within the other 

 (fig. 122) ; the uniformly thickened walls of which, composed of 



concentric lavers, often 

 enclose merely a minute 

 cavity, with a shrunken 

 nucleus ; and besides 

 .$ these, smaller cells fre- 

 quently in process of dis- 

 solution, isolated or ag- 

 gregated together ; and, 

 lastly, an indistinctly fibrous or granular matrix, not un- 

 frequently observed in a state of disintegration, and a con- 

 siderable quantity of fluid contained in larger or smaller 

 areolar spaces in it. The more central portions of this 

 fibrous substance gradually pass into a thin, hard, y el- 

 Fig. 122. Cells from the gelatinous nucleus of the lig. intervertebralia : 1, large 

 parent cell, a, with a septum derived from two secondary cells of the first generation, 

 and five secondary cells! b, of the second generation ; with concentrically thickened 

 walls and shrunken nuclei, c, in the small cell cavities : 2, parent cells, a, with two 

 secondary cells, separated by a delicate septum, /', and which, with uniformly thickened 

 walls, contain a minute cavity and shrunken nucleus, c. 



