INTERCELLULAR SUBSTANCE. 



been very generally concluded that the matrix was depo- 

 sited between the cells, and hence this was called " inter- 

 cellular substance." But it must not be supposed that 

 epithelium is in all cases to be distinguished from cartilage 

 by the existence of separate cells. In many forms of epi- 

 thelium at an early period of formation, the formed material 

 corresponding to the several masses of germinal matter is 

 continuous throughout, and presents no indications of divi- 

 sion into separate cells. This is well seen in the lower 

 part of the specimen represented in pi. IV, but in fig. 13, 

 pi. V, an unusually striking example of this is given. The 

 specimen was taken from the deeper portion of the con- 

 junctival epithelium of man. Not only is there no indi- 

 cation of division into distinct cells, but the structure 

 would be described as a matrix exhibiting spaces occu- 

 pied by the masses of germinal matter. The arrange- 

 ment exactly corresponds with that existing in the case of 

 cartilage, and the masses of germinal matter with a thin 

 investment of formed material may be removed just as in 

 that tissue. It is, therefore, clearly erroneous to consider 

 cartilage and epithelium as representatives of different classes 

 of tissues. The analogy between them will be at once under- 

 stood by a glance at fig. 13, and fig. 15, which have been 

 carefully copied from actual specimens. In fig. 14, a portion 

 of older epithelium from the same surface is represented. 

 In this, each mass of germinal matter is invested with its 

 own layers of formed material, and these are distinct from 

 neighbouring portions. A " cell," or elementary part of 

 fully-formed cartilage and tendon, consists of a mass of 

 germinal matter, with a proportion of formed material 



E 2 



