I)'-' HISTOLOUY. 



In support of Schwaun's theory is the fact that fibrillar 

 connective tissue contains a decreasing number of cells as auv 

 advances, while at the same time the fibres increase largely. 

 But it is certain that the decrease in cells is only a relative one. 

 As the organism grows more space is left for the intercellular 

 substance, and in older connective tissue cells become apparently 

 less numerous. This theory, in the light of later investigations, 

 has lost its adherents. It is to be noted that between the cellu- 

 lar and intercellular theories there is no essential difference. 

 The ground substance is a product of the cells, which exercise a 

 nutritive, and formative influence on the intercellular substance 

 and regulate all processes going on therein. In other words. 

 the cells are the only elements playing an active role in the 

 tissue. According to the cellular theory, the cells form the 

 fibres directly ; while according to Virchow's view, the fibres 

 arise indirectly from the cells which have first formed inter- 

 cellular substance. In this intercellular substance a differen- 

 tiation takes place under the influence of cells. One may take 

 up a position half-way between these two theories. Flemming 

 states this as follows : " There is formed in the peripheral part 

 of the cell a fibrillar layer ; this layer becomes intercellular 

 substance, increases in quantity, and may produce new fibrils as 

 long as it grows." He believes that " the intercellular substance 

 is not dead or inert, but is a material produced from the cells 

 by a chemical and structural modification, and is capable for a 

 long time of producing fibrils." This has been confirmed by 

 the work of Mall. 



With regard to the formation of elastic fibres there are also 

 two hypotheses. Some regard them as intercellular ; others, as 

 intracellular in origin. The old idea that the nucleus or the 

 whole cell is transformed into elastic fibres is without foun- 

 dation. Mainly on the ground of investigations of the develop- 

 ment of elastic cartilage has it been determined that the elastic 

 fibres arise entirely in the hyaline ground substance, and have 

 only an indirect relation to the cartilage cells (Miiller, v. 

 Kolliker, Ranvier, Mall). According to Mall, they appear as 

 delicate fibrils in the ground substance midway between the 



