462 CHAPTER 62. 



All that we need do or perhaps I * should rather say, all that \ve can 

 do in shoeing is to preserve the outer case whole and entire ; namely, 

 the Crust and Bars, the Sole and the Frog. Nature in most cases takes 

 care of the interior structures, if we preserve the outer case. The excep- 

 tions to this rule are diseases resulting from constitutional or accidental 



o 



causes. 



But if we do not preserve the outer case whole and entire, the interior 

 structures will certainly suffer in various ways, to be described hereafter. 



942. Of the outer case of the Foot. 



The outer case consists of three parts, viz. 1st, the Crust, otherwise 

 called the Wall (Plate 47, A, fig. 1), and the Bars ; 2nd, the Sole (B, fig. 

 2) ; 3rd, the Frog (c, fig. 1). The Bars are not shown in this drawing. 

 See B, fig. 6. 



943. Of the Crust or Wall 



The Crust or Wall (A, fig. 1) will suffer if it be rasped outxide. It con- 

 sists of a number of fibres (containing a soft cellular nutritive material), 

 running down longitudinally from the coronet. In technical language 

 the crust is said to be secreted by the plexus of blood-vessels round the 

 coronet, called the coronary band or cushion. In plainer words, it grows 

 from the thickened skin round the coronet (B, fig. 1). In the human 

 fingers the nails grow in a similar way from the skin. The crust is over- 

 laid externally by a gluey glazed superficial layer of which hereafter. 



The fibres of the crust contain the above-mentioned soft cellular mate- 

 rial in an organised form for a considerable, perhaps two thirds of the 

 distance down. In their lower portion the crust becomes dry and hard ; 

 and the fibres are then in a condition, first, to stand wear and pressure 

 without sensation ; and, secondly, they are in a state almost ready, and 

 in their lowest portions quite ready, not exactly to be cast off, but to be 

 worn off by friction with the ground. The fibres are constantly being 

 renewed by growth from above. 



No doubt under the wise laws of nature the renewal or rate of growth 

 is exactly proportioned to that amount of wear which would be incidental 

 to a horse in a state of nature, such as would be required for obtaining 

 food and water. I am aware that when horses are turned out in this 

 country in a field with no distance to go in search of food or water, this 

 natural wear does not sufficiently take place, and in consequence the feet 

 become long. But it must be remembered that this is a semi-artificial 

 condition. A horse really in a state of nature would probably have to 

 travel many miles a day in search of food and water. 



I may here remark, if the reader will pardon a short digression, that 

 nature appears to furnish horses with feet suitable to the locality in 

 which they are bred. The low-bred horse, which is a native of rich wet 

 pastures, where he would not have far to travel in search of food and 

 water, has usually large, wide, somewhat fiat, " fieshy " feet. Such feet 

 are more convenient to the animal in such pastures than narrow and more 



