32 



THE ANTELOPE OF AMERICA. 



It will be observed, on examining Fig. 1, that the outer part 

 of the skin h, presents an irregular corrugated appearance, occa- 

 sioned by protuberances and depressions, called fa'pillce^ varying 

 considerably in height and depth. With this uneven surface 

 terminate those blood-vessels of the skin which carry the red 

 blood in sufficient quantities to produce a stain. Upon this un- 

 even surface rests the epidermis, or the outside coating of the 



Fig. 2 



T\c^ \ 





.±L. 



OF AN INCH X 60. 



OF AN INCH X 296. 



Thin section of a growing liorn of an antelope, cut perpendicular to the surface. 

 Fig. 1 shows the general structure under a low power. Fig. 2, more highly magni- 

 fied, shows the cell structure. The letters refer to the same parts in each figure. 



a. The connective tissue continuous with the periosteum of the core of the horn. 



b. The papillae, very large and irregular. 



c. The cell growth upon the papilliB. 



d. The outer portion, seen to be made up of the flattened and desiccated cells of the 

 layer beneath, already converted into horn. 



skin. If this appears to want uniformity of structure, a critical 

 examination shows that this results from a change of form of the 

 cells of which it is composed, which become flattened and consol- 

 idated by compression, and by evaporation, or by becoming dried 

 up. Thus is the epidermis converted into true horn. Chem- 

 ically, the constituents of epidermis and of horn are nearly iden- 

 tical. The true horn at d is but the flattened and dried up cells 

 which were formed upon the papillae ^, and were pushed up by 

 new cell formations beneath them, till they reach their final form 



