54 DISEASES OF THE HORSE'S FOOT 



tissue. Each point of the ingrowing lines of the echelon 

 has usually one cell further advanced into the corium than 

 its neighbors, and may be termed the apieal cell. The 

 fine basement membrane separating epithelium from corium 

 is still clearly evident. This epidermal irruption of the 

 corium takes place at definite points right round the foot. 

 It is extremely probable, however, that it commences first 

 at the toe and spreads laterally. 



As yet, these cellular ingrowths (which are destined to be 



3* 



Fig. 28. — Section from Calf Embryo. 



The epithelial ingrowths hang down from the epidermis into the 

 corium like the teeth of a comb (Mettam). 



the horny laminae, and cut up the corium into sensitive 

 laminae) are free from irregularities or secondary laminae. 

 Before these are to be observed other changes in connection 

 with the ingrowths are to be noticed. 



The first is merely that of elongation of the epithelial 

 processes into the connective tissue, until the rete Malpighii 

 gives one the impression that it has hanging to its under- 

 neath surface and into the corium a number of thorn-like 

 processes. These extend all round the front of the foot, 

 and even in great part behind. Accompanying this elonga- 



