ELASTICITY OF NATURAL HORN. 89 



much wear that the increased activity of the horn-forming vessels 

 cannot make up the deficiency. Now, as has been demonsti-ated in 

 previous articles, the foot entirely unprotected (under certain condi- 

 tions) may wear away so much at the toe as to. cause serious lame- 

 ness. Even this is not so likely to be the case as many imagine, and 

 in many experiments I have found that an unshod foot Avill stand far 

 more attrition than was supjiosed to be possible. But to give the 

 foot a fair chance, it must be in a sound condition to start with. If 

 it has been rendered weak by a non-use of the parts which nature 

 intended to do a share of the work, it will not stand the test ixnder 

 the most favorable circumstances. 



The hoi-se which has worn shoes for any length of time will soon 

 go lame when without their protection. The smith has destroyed 

 the capacity for resistance, and there must be a continuance of the 

 system that has destroyed, or opportunity to recover from the treat- 

 ment. The growth of the hora has not only been curtailed, but that 

 which is de}x>sited is of an inferior character. It may appear para- 

 doxical to state that as the horn becomes harder it is more rapidly 

 worn away by the attrition of the i-oads. It will be undei-stood, 

 however, when a comparison is made between the horn from an un- 

 shod foot and that which has worn iron for a length of time. The 

 former cuts more easily when the tool used is a sharp knife, but a 

 rasp has less effect. One is an elastic, live material, pliable as a 

 piece of whalebone ; the other a brittle substance, almost as destitute 

 of toughness as the horn fi-om a dead animal. IVIr. Douglas, an 

 English Avi-iter, states : "If the crust is closely examined with a 

 microscope, its structure will be found to consist of a number of 

 bristle^like fibers standing on end, but leaning diagonally towards 

 the ground. Fi-om the particular longitudinal construction of the 

 fibers, it follows that they will bear a great amount of weight so long 

 as they are kept in a natural state. The cinist so viewed resembles 

 a number of small tubes, bound together by a hardened, glue-like 

 substance." 



" Whoever has seen a Mitrailleuse gun, with its numerous ban-els 

 all soldered together, can form a very good idea of the peculiar stiiic- 

 ture of the cinist (or wall), especially if they were likewise to imagine 



