840 K. J. GOSS 



of necessity bulged laterally on all sides ( Fig. 14 ) . The attachments 

 of the old antler to the pedicle were conconiitantK disrupted. 

 Nevertheless, this loosened antler remained attached bv its screw, 

 while the pedicle skin healed the wound beneath it. Prevented from 

 growing as a direct extension of the pedicle, the new antler re- 

 generated a straight, unbranched protuberance from its posterior 

 margin. When the old antler was finally shed, there was revealed a 

 flattened disc of abortive antler tissue overlving the pedicle (Fig. 

 15). Apparently in this case growth pressure was responsible for the 

 eventual detachment of the old antler, which in fact had been 

 physiologicallv shed some 7 weeks before. During the rest of the 

 summer, the posterior branch grew almost as long as the opposite 

 control antler, while another twisted outgrowth was produced be- 

 latedly from the center of the pedicle (Fig. 16). 



Thus, shedding of the old antler is not prerequisite to regenera- 

 tion of the new one. Rather, its detachment coincides with the in- 

 itiation of renewed growth. Indeed, one never occurs without the 

 other, except in cases where replacement of the antler may be 

 secondarilv delayed after healing of the pedicle, as in older males 

 of certain species that shed their antlers in the autumn but do not 

 resume growth until spring. Whatever may be the nature of the 

 regulating mechanism(s), it is not improbable that shedding and 

 regrowth are simultaneous reactions to a common stimulus. 



Control of Antler Shedding 



Influence of Environmental Factors 



The seasonal nature of antler shedding strongly implicates the 

 operation of one or more environmental factors as the stimulating 

 agent(s). Mediated through secondarv phvsiological mechanisms, 

 such influences are probably also responsible for many other annual 

 occurrences in deer, e.g., molting, color changes, migrations, and 

 the various events associated with the reproductive cycle. Though 

 each species of deer sheds its antlers at a characteristic season, the 

 variations among different kinds of deer are considerable even in 

 the same geographical area. For example, in the north temperate 

 regions, shedding may occur in the fall, winter, or spring. In adult 



