THE WHITE LINE. 87 



small, whitish, parallel streaks lying close together. The 

 intervals between the separate horny lamina;, filled, within the 

 foot, by the sensitive laminae, are in the white line occupied by 

 a yellowish, semi-transparent, waxy horn (fig. 52, d), which is 

 softer and more yielding than the horn of the sole. This horn 

 is produced by the papillae, which are situated on the border 

 between sensitive wall and sensitive sole, and are in many 

 cases merely the terminations of sensitive laminae. 



The mixed horn of the white line is soft, breaks down more 

 readily than that of the sole, forming a whitish pulverulent 

 material, easily distinguished by its colour from the horn of 

 the wall and sole, hence the name " white line." 



The white line is of special importance in shoeing, as it 

 indicates the thickness of the wall. Separation between the 

 horny wall and horny sole in the white line gives rise to the 

 condition termed " loose wall." 



Wherever the horny wall exhibits horny laminae, it must 

 necessarily show the " white line." On close examination it 

 will be found that the white line does not cease at the angle 

 of the bars, but that it is reflected, precisely like the horny 

 wall, and runs forwards and inwards, at an angle, towards its 

 fellow, dividing the sole from the bars for about half the 

 length of the frog (figs. 45 and 46, g). It is certainly not so 

 apparent here as at the circumference of the sole, but this 

 is explained by the fact that the corresponding portion of the 

 laminal sheath is slender, and has thinner and fewer horny 

 laminae than the other parts : also, and principally, because 

 the bars grow obliquely outwards and downwards, and, there- 

 fore, tend to cover these parts of the white line. In order 

 to see the white line at this point, a considerable portion of 

 the bar must be removed. In front of the anterior third of 

 the frog it is no longer visible, the bars and sole here being 

 united. 



