Principles Of VExERiisTARV surGErY 35 



glands. An old liver-scar may contain cyst-like cavities sur- 

 rounded with epithelium somewrhat like liver cells, while a 

 scar forming in the kidney may show tubular formations. 



Certain compensatory changes may occur if a large por- 

 tion of a gland is removed or if one of the kidneys is re- 

 moved : the remaining portion or gland undergoes hyper- 

 trophy, the cells increase in number, showing marked karyo- 

 kinetic division of' nuclei, so that a loss of volume may be 

 completely made good in a comparatively short time. 



HOOF. — Hoof, horn and claws are products of epithe- 

 lium. They proceed from a matrix that is rich in cells hav- 

 ing a special function to perform — that of secreting the in- 

 sensitive hoof, horn or claw fibres. This matrix is analogous 

 to the hair follicle which performs the function of secreting 

 the hair. If a part of a hair follicle remains intact the remain- 

 ing cells will immediately proceed to reproduce a new hair, 

 and if a part of the hoof, horn or claw matrix is left in any 

 given part the fibers for a new insensitive organ (hoof, horn 

 or claw) will soon be reproduced by the same genetic pro- 

 cess. That is to say, hoof, horn or claw tissue will promptly 

 regenerate by the outward growth of new fibers from the 

 genetic matrix, so long as the latter is not destroyed. When 

 there is loss of matrix in whole or in part, it, too, is capable 

 of regenerating, but the quality of fiber thereafter produced 

 may be defective. Thus, if the coronary cushion of a horse 

 or ox is partially destroyed, the wall of the hoof proceeding 

 from the regenerated matrix will be abnormal. If a portion 

 of the sensitive laminee is destroyed by disease or injury, 

 the wall will never again be perfectly united to the sub- 

 jacent regenerated laminae. 



The hoof of the horse is divided into wall, sole and frog, 

 all of which are secreted by a highly organized matrix — the 

 keratogerious membrane, — which occupies the confined posi- 

 tion between the hoof and the bones. This genetic structure 



