8G SEXUAL DIMORPHISM 



the small forked antler of the existing muntjacs, although 

 shed every year, does not increase in size or complexity. 

 This may be due merely to a difference in the degree of 

 irritation, especially considering that the muntjac in fighting 

 uses its canine teeth, as well as its antlers. 



I am well aware that the above suggestions are very 

 speculative, and to many readers they may seem entirely 

 without foundation. There are, however, certain established 

 and accepted facts which, I believe, cannot be ignored in 

 considering the physiology and evolution of antlers, namely, 

 the facts concerning the development of exostoses as the 

 result of mechanical irritation. Having but a limited know- 

 ledge of comparative pathology myself, I will refer to certain 

 statements in an authoritative manual of veterinary surgery. 1 

 It is here stated that "in horses periostitis sometimes 

 develops on the lower margin of the mandible, at the level 

 of the first molar tooth. External stimulation, especially 

 knocks against narrow cribs in feeding, generally cause this 

 malady. The exostoses so formed are sometimes flat, but 

 usually round, well-defined, and often stalked. They are 

 painless, and firmly connected to the bone." These exostoses 

 are not deciduous, and remain covered with skin. 



In another chapter of the same work, the injuries due to 

 pressure of the bit on the diastema, or toothless part of the 

 lower jaw, are described. This sometimes causes a periostitis 

 ossificans, which leads to the formation of exostoses, and on 

 the skeletons of old saddle-horses these are often found. 

 Sometimes it leads to periostitis purtdenta, which affects 

 the substance of the bone, and causes necrosis or death of 

 portions of it. Dead pieces of bone, as big as a finger, are 

 sometimes expelled through abscesses on the lower margin 

 of the mandible. The latter process is not similar to the 



1 Lehrbiich der s-pcciellen Chirurgie fur TJiicrarzte, Dr. H. M oiler, Stutt- 

 gart, 1891. 



