38 



THE CONNECTIVE TISSUES 



[CH. rv. 



acid, or after staining with such dyes as magenta and orcein, for which 

 elastic fibres have a great affinity. They are bigger than the white 



FIG. 52. Horizontal preparation of the cornea of 

 frog, stained with gold chloride ; showing the 

 network of branched corneal corpuscles. The 

 ground substance is completely colourless, 

 x 400. (Klein.) 



FIG. 53. Ramified pigment- 

 cells, from the tissue of 

 the choroid coat of the 

 eye. x 350. a, Cell with 

 pigment ; b, colourless 

 fusiform cells. (Kdlli- 

 ker.) 



fibres, have a distinct outline, and a straight course ; they run singly, 



branch, and join neighbouring fibres (fig. 50). 



The material of which the elastic fibres are composed is called 

 elastin ; this is another albuminoid. It 

 is unaltered, as we have seen, by dilute 

 acid. It also resists the action of very 

 strong! acid, and is not affected by boiling 

 water. 



The bundles of white fibres which have 

 been swollen out by dilute acetic acid 

 sometimes exhibit constrictions as in 

 fig. 51. These are due to elastic fibres or 

 cell processes encircling them and pre- 

 venting the swelling at those points. 



Connective-tissue corpuscles. These are 

 the cells of connective tissue: several 

 varieties may be made out, especially 

 after a preparation has been stained. 



1. Flattened cells, branched, and often 



united by their processes, as in 

 the cornea. 



2. Flattened cells, unbranched, and 



joined edge to edge like the cells of an epithelium ; these are 

 well seen in the sheath of a tendon. 



3. Plasma cells of Waldeyer, varying greatly in size and form, 

 but not flattened. The protoplasm is much vacuolated. 



FIG. 54. Flat, pigmeuted, branched 

 connective-tissue cells from the 

 sheath of a large blood-vessel of 

 the frog's mesentery ; the pigment 

 is not distributed uniformly 

 throughout the substance of the 

 larger cell, consequently some 

 parts of it look blacker than others 

 (uncontracted state). In the two 

 smaller cells most of the pigment 

 is withdrawn into the cell-body, so 

 that they appear smaller, blacker, 

 and less branched, x 350. (Klein 

 and Noble Smith.) 



