GENERAL OBSERVATIONS 57 
removed by operation or by accident (see reported cases in 
Chapter VII.). 
The activity of the cells of the rete Malpighii of the 
corlum covering the remainder of the foot will be quite 
as necessary as the activity of the cells of the coronary 
papille which form the horn tubes themselves. ‘For,’ 
in Professor Mettam’s own words, ‘I am inclined to believe 
that much of the “ white line’ which is found uniting the 
Fic. 30.—Srection THroucH Hoor anp Sorr Tissues oF A FoAL At 
TERM. 
The horn of the wall is shown, and the horn-core (‘horny laminz’) of the 
epithelial ingrowth. The latter has advanced far into the corium, and is 
now provided with abundant secondary laminar ridges (Mettam). 
wall of the hoof to the sole has been derived from the horn 
formed from the rete of the foot corium. This origin will 
explain the absence of pigment from this thin uniting 
“line,” as it does from the horn lining the interior of 
the wall. The cells of the rete are free of colouring 
matter.’ 
From the matter here given us it is easy to understand 
how, in a macerated foot, the appearance is given of inter- 
