CHAPTER IV. 



THE ELASTIC TISSUES OF THE FOOT. 



To those portions of the horse's foot just described must be 

 added other structures, which prolong and complete the former : 

 the two lateral cartilages and the plantar cushion. These are 

 pecuUar to the horse, and do not occur in the same form in 

 the foot of any other animal. They, therefore, differentiate the 

 equine foot from all others, and, on account of their structure, 

 form, and functions, deserve our closest attention. The fact of 

 physical peculiarities rendering them of such great importance, 

 leads us to very shortly describe the two commonest forms : 

 cartilage and elastic tissue. 



Cartilages are, in simple language, close-grained, firm tissues, 

 which, when fresh, present a whitish, when dried, a browii 

 colour. They are moderately firm in texture, exceedingly 

 tough, insensitive, and almost non-vascular. In addition to 

 toughness they show a high degree of flexibility and elasticity, 

 especially when in moderately-thin plates or when mixed with 

 other fibrous or tendinous tissue, as in " fibro-cartilage." In 

 the animal body, cartilage not only forms a component of joints, 

 in which we have already found it occurring as articular 

 cartilage, but enters into the composition of many parts, which, 

 while possessing a distinct form, are also distinctly flexible. 



Elastic tissue is widely distributed throughout the animal 

 organism, and is found associated with connective or cellular 

 tissue, of which it is a variety. The parts in which elastic 

 tissue predominates are distinguished by a yellow colour. 

 Microscopical examination shows this tissue to consist of fine 

 fibres uniting with one another and forming a kind of net. 

 The smallest accumulations of such fibres are associated to form 

 bundles, smaller and larger cords, bands, or entire tissues. The 

 ends of the fine threads, when ruptured, curl up ; and the larger, 



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