98 



HISTOLOGY OF HOKN. 



the horny lamina all consist of cells, which are variously 

 described as tubular, and inter- tubular or connective cells. 



Leisering states that, in general^ the 

 cells of the soft horn and of the sole 

 are larger than those of the wall. 

 The cells of the horny laminse are 

 longer and less thick than those of 

 other portions of the hoof. Young, 

 imperfectly cornified cells lying close 

 to their point of formation (papillae, 

 sensitive laminse) are rounded, soft, 

 and soon disappear after the addition 

 of caustic potash solution ; they are, 

 therefore, better studied in dilute 

 *?reSTSu%'Sner,,';Wug "oetic acid, which destroys them less 



sensitive wall ; b, older cells from rqi-)iHl y 

 a fragment of horn lamina (treated '^1 J ' 



with caustic potash). Lciseriug believes that the cells of 



the horn tubes lie with their greatest length in the direction of 

 the tube ; the inter-tubular cells, however, at right angles to the 



tube. The tubular 

 and connecting cells, 

 therefore, cross more 

 or less in direction. 

 This is well shown in 

 sections of the soft 

 horn of the frog, where 

 the cells cross almost 

 at right angles (fig. 

 65). Leisering has ob- 

 served the same fact 



Fig. 64.— Horizontal section of a fragment of cast horn lU tllC middle shcath 



from sole. The horn tubes a, like the inter-tubular horn p ,i it • -ii 



b, are seen to consist of cells. At c some of the horn 01 tUe Wall, especially 



tubes have been torn away. • i, i: j • 



m young hoots and m 

 such as have been long macerated. In the sole the formation 

 is somewhat different. The tubular cells there lie with their 

 greatest length more nearly transverse to the direction of the 

 tube. Perhaps this position of the cells and the less intimate 

 connection which exists between them throughout the sole 

 explain the flaking of the sole during work. The cells of the 

 horny laminae always lie with their greatest length across the 



