THE HORNS AND ANTLERS OF RUMINANTS. 287 



the facts at our disposal, were of quite indefinite recurrence, as 

 with certain species in tropical India to-day. " Throughout the 

 Tertiary period tropical conditions prevailed far into the tem- 

 perate regions" (Wallace); and it is significant that, "with one 

 exception, all the Pliocene Deer which can be brought into 

 relation with living forms are closely allied " to existing Oriental 

 species (Boyd Dawkins). Of Sambur and Axis we read in 

 Mr. Blanford's authoritative work, * The Fauna of British India,* 

 that " stags with perfect antlers may be found at all seasons," 

 and of the first-named Deer, which represents the most widely- 

 distributed Oriental species, that " individual stags retain their 

 horns for successive years." These facts have an important 

 bearing upon the protective value of antlers to the Tertiary Deer, 

 for they enable us to infer the constant presence of armed males 

 in a herd. 



Why the Deer of temperate regions carry their antlers for not 

 more than eight or nine months, and the circumpolar species 

 only for three or four, is a question which claims further in- 

 vestigation ; but the ascertained facts lend great probability to 

 Prof. Martin Duncan's view that the creeping in of a colder 

 climate at the close of the Tertiary period, affecting the blood- 

 supply so as to induce a failure of nutrition, caused antlers 

 that were relatively permanent in the Pliocene tropics to 

 become relatively deciduous during the glacial conditions that 

 supervened.* 



IV. Sex. 



Weapons which owe their origin and purpose to protective 

 adaptation must have been profitable to both sexes, and their 



* The origin of deciduous weapons must be sought in the wider subject 

 of physiological regeneration. Power to renew a lost part is present in 

 various groups of animals, though in different degree, and is probably due to 

 adaptation through selection, as suggested by Prof. Weismann, who points 

 out, in support of his view, that the capacity for regeneration appears 

 specially in parts which are of biological importance, and are at the same 

 time exposed to frequent injury or loss. From the fact that primitive antlers 

 were constitutionally brittle and liable to separation by fracture, while 

 valuable as a means of defence, it seems legitimate to infer that some 

 physiological stimulus, similar to that which provides the Lizard with a new 

 tail, must have provided the Miocene Deer with new antlers. The burr, or 

 coronet, of to-day marks the original point of fracture and subsequent seat of 

 renewal) the skin-covered pedicel having survived (so to speak) in statu quo. 



