THE CONNECTIVE TISSUE 33 



Epithelium is likewise concerned in the processes of transudation, 

 diffusion, and absorption. 



II. THE CONNECTIVE TISSUES. 



This group of tissues forms the skeleton with its various connections 

 bones, cartilages, and ligaments and also affords a supporting framework 

 and investment to the various organs composed of nervous, muscular, and 

 glandular tissue. Its chief function is the mechanical one of support, and 

 for this purpose it is so intimately interwoven with nearly all the textures of 

 the body that if all other tissues could be removed, and the connective tissues 

 left, we should have a wonderfully exact model of almost every organ and 

 tissue in the body. 



General Structure of Connective Tissue. The connective tissue is 

 made up of two chief elements, namely, cells and intercellular or formed 

 substance. 



FIG. 37. Horizontal Preparation of the Cornea of Frog, Stained in Gold Chloride; 

 showing the network of branched corneal corpuscles. The ground substance is completely 

 colorless. X 400. (Klein.) 



Cells. The cells are usually of an oval shape, often with branched 

 processes, which are united to form a network. They are most readily 

 observed in the cornea, in which they are arranged, layer above layer, parallel 

 to the free surface. They lie in spaces in the intercellular or ground sub- 

 stance, which form by anastomosis a system of branching canals freely 

 communicating, figure 37. 



The flattened tendon corpuscles which are arranged in long lines or rows 

 parallel to the fibers belong to this class of cells, figure 39. 



These branched cells often contain pigment granules, giving them a dark 

 appearance; they form one variety of pigment cell. Pigment cells of this 

 kind are found in the outer layers of the choroid. In many of the lower ani- 

 3 



