4 
A. ZUNDEL. 
tiply, and flatten into lamellae, in the direction of the surface of 
the keratogenous membrane, as they spread from it. The wall 
then grows from its superior to the inferior border, and the other 
parts of the wall from their internal to their external face. The 
villosities of the coronary band and of the velvety tissue are the 
organs around which accumulate the epithelial cells; their pres¬ 
ence defines, consequently, the tubular structure of the horn. 
The laminae, in the physiological state, do not co-operate in 
a sensible manner with the formation of the wall; the keraphyl- 
lous laminae form themselves at the coronary band, at the origin 
of the podophyllous; they descend with the wall, gliding at the 
surface of the layer of cells which separates them from the lami¬ 
nated tissue, a movement of descent which is facilitated, however, 
by the multiplication in the same direction of the said cells. 
When the podophyllous tissue [is inflamed, whether exposed or 
not, its latent activity soon manifests itself. It gives rise to a 
great quantity of hard horn, hollowed, as seen by Gourdon, with 
tubes, and oblique in a direction backward. These tubes, more 
irregular than those of the normal wall, are disposed in a parallel 
series; they are in form, round, villo-papillae, which have devel¬ 
oped on the face border of the laminae. In these cases of pro¬ 
duction of horn by the action of the podophyllous tissue alone, 
one never sees, between the sensitive laminae, distinctly formed 
horny laminae in the middle of the other cells, as it is observed 
in the wall proceeding from the coronary band. The horn which 
rises on the surface of the podophyllous, immediately after the 
removal of a piece of the wall, is not a permanent one; it must 
be replaced by the horn of the coronary band. This change is 
complete, microscopical examination proving that the wall which 
descends from the coronary band, provided with keraphyllous 
laminae, engages itself under the temporary wall, and slides by 
the action already described over the surface of the soft cells of 
the laminated tissue. As soon as this tissue, modified by inflam¬ 
mation, is covered over by the permanent wall, its papillae become 
atrophied, and its action returns to the limited boundaries of 
physiological condition. ( Chauveau .) 
The foot is an organ of support and an apparatus of elasticity ; 
