THE FOOT 66y 



is indicated by a white line (Fig. 228, 7) which runs around the entire 

 junction of sole and wall. The white line represents the layer of the 

 wall next to the insensitive laminae (Fig. 231, 6) ; within this come 

 the terminal ends of the laminae themselves, and between these and 

 the sole a layer of much softer yellowish plastic horn (Fig. 229, 6). 

 This cement substance is secreted by the four or five papillae found 

 on the end of the sensitive laminae, shown diagrammatically and 

 microscopically in Fig. 232. The soft cement substance, besides 

 ensuring the union of wall and sole, also admits of slight yielding 

 of the sole, to which reference will be made later. A microscopical 



Fig. 231. — Horizontal Section through the Foot, One Inch above and 

 Parallel to the Ground. 



i, The wall ; 2, its inflections at the heels ; 3, the bars and convexity of the sole 

 caught in the section ; 4, pa r t of the pedal bone ; 5, portion of the plantar 

 cushion ; 6, the white inner layer of horn between the sensitive laminae and 

 the outer wall. 



examination of the union shows the horn laminae digitating with 

 the sole between the laminae, which are now wavy, and no longer 

 in possession of secondary laminae. The horn is arranged in con- 

 centric layers, being formed by the four or five secreting papillae on 

 the terminal end of the sensitive laminae. 



The Foot-pad, or ' frog,' as it is vulgarly known, is a pyramidal- 

 shaped piece of horn, accurately moulded over the plantar cushion, 

 and filling up the space left by the inflection of the wall at the 

 posterior part of the foot (Fig. 228,7, 2, 3, S) . In the foot-pad we meet 

 for the first time a peculiar soft elastic horn, possessing something of 

 the characters and appearance of india-rubber. The horn fibres of this 

 structure are wavy, arranged in strata which run at right angles to 



