HORSESHOEING. 53 



lure is called a horn-tube, and the lighter-colored masses of horn (Fig. 

 36, b) between the tubes are known as intertubular horn. 



With the exception of the horny leaves of the wall and 

 bars, all the horn of the hoof is composed of horn-tubes and 

 intertubular horn. 



The horn-tubes of the wall, sole, and frog always run down- 

 ward and forward parallel to the direction of the wall at the 

 toe, — that is, in a direction parallel with the inclination of the 

 hoof as a whole. Although the wall, sole, and frog differ from 

 one another considerably with respect to the size and number 

 of the horn-tubes, the quality of the intertubular horn, and the 

 thickness and strength of the horn-cells, these differences are 

 only of subordinate interest or importance to the horseshoer ; 

 but he who desires to learn more of this matter is referred to 

 the work of Leisering & Hartmann, " Der Fuss des Pferdes in 

 Riicksicht auf Bau, Verrichtungen und Hufbeschlag," eighth 

 edition, Dresden, 1893. This book also treats of the variations 

 in the quality of hoofs, which is very important for the practical 

 horse-shoer to know. It, furthermore, considers the solidity 

 and strength of the horn of the different parts of the hoof. 



With respect to solidity, two kinds of horn are distinguished, — 

 namely, hard and soft horn. The periople, the white line, and the 

 frog are soft horn structures ; the middle layer of the wall and the 

 sole are hard or solid horn. The wall, however, is somewhat 

 harder and more tenacious than the sole, for the latter passes 

 off in more or less large flakes fexfoliates) or crumbles away on 

 its lower surface, at least in shod feet, while no such spontaneous 

 shortening occurs in the wall. 



Soft horn differs from hard horn in that its horn-cells never 

 become hard and horn-like. It is very elastic, absorbs water 

 quickly, and as readily dries out and becomes very hard and 

 brittle and easily fissured and chapped. With respect to quality, 

 we distinguish good and bad horn ; the former is fine and tena- 

 cious (tough), the latter coarse and either soft and crumbling or 



