THE FOOT 



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cells and stains them red. whilst the picric acid stains all tissue 

 a yellow colour which has undergone the process of keratinisation. 

 By means of this stain it is easy to determine the character of the 

 horn under examination. 



The ultimate horn cell is a very thin, spindle-shaped, oblong, or 

 irregular body (Fig. 234), containing granular matter, a nucleus, 



Fig. 233. — Vertical Section through the Foot, at a Point Two-Thirds 

 the Distance from the Toe to the Bulbs of the Heel. 



r, The lateral cartilages ; 2, heel of the pedal bone ; 3, the foot-pad ; 4, the sensitive 

 laminae ; 5, the ' bars.' 



Fig. 234. — Horizontal Section of the Horn of the Wall, Highly 

 Magnified. 



Horn tube, a canal containing cellular elements ; b, the tubular horn — that is, 

 the horn secreted from the papilla, forming an oval or circular nest of cells 

 around the canal ; c, the intertubular horn. 



and frequently pigment. In all cases the cells are united at then- 

 edges and sides by a cement substance. By acting upon horn with 

 caustic alkalies, the cells are in the first instance rendered clear; 

 they then gradually dissolve, are converted into a gelatinous mass, 

 and finally disappear. Bearing in mind the highly alkaline nature 

 of decomposing urine, owing to the presence of free ammonia, the 



