104 



THE HUMAN BODY. 



yields gelatin when boiled in water. The Substance in it, 

 and in the bones, which is turned into gelatin by such 

 treatment is known as collagen. Glue is impure gelatin 

 obtained from tendons and ligaments, and calfs-foot 

 jelly, so often recommended to invalids, is a purer form of 

 the same substance obtained by boiling the feet of calves, 

 which contain the tendons of many muscles passing from 

 the leg to the foot. 



FIG. 43. 



FIG. 43a. 



FIG. 43. White fibrous connective tissue, highly magnified. The nucleated 

 corpuscles, seen edgewise and appearing spindle-shaped, are sesn here and 

 there on the surface of the bundles of fibres. 



FIG. 43a. Yellow elastic tissue, magnified after its fibres have been torn 

 apart. 



Elastic Tissue. This is almost invariably mixed in some 

 proportion in all specimens of white fibrous tissue, even 

 the purest, such as the tendons of muscles; but in certain 

 places it exists almost alone, as for example in the liga- 

 ments (ligamenta subflava) between the arches of the 

 vertebra, and in the coats of the larger arteries. In quad- 

 rupeds it forms the great ligament already referred to (p. 

 84), which helps to sustain the head. This tissue, in 



