THE HORNS AND ANTLERS OP RUMINANTS. 245 



the Wapiti Deer confined in his park at Ottawa, that the largest 

 antlers ever grown in his grounds were carried by a medium-sized 

 Deer who, in common with several others, was always subject to 

 the control of a larger Deer with smaller antlers than any of 

 them. But a theory relating to wild animals may reasonably 

 object to arguments drawn from domestic or semi-domesticated 

 subjects, reared in artificial conditions and leading an artificial 

 life, from which we can infer only what will happen if the condi- 

 tions remain the same. Our experimentum cruris, or crucial test, 

 must relate to ruminants in a state of nature, and under circum- 

 stances which place the issue beyond the shadow of a doubt. 

 Dr. Wallace has observed with justice that "the power of 

 predicting what will happen in a given case is always considered 

 to be a crucial test of a true theory ; " and to this we may add 

 that when the predicted event happens to be the one legitimate 

 deduction from our assumed premisses, a conflicting result is 

 necessarily fatal to the hypothesis. In the common stag we have 

 the typical member of a group (Cervus) endowed with remarkably 

 combative instincts and possessed of remarkably formidable 

 weapons. These weapons are limited by inheritance to the 

 males, and, according to the theory of sexual selection, have 

 undoubtedly been acquired as sexual weapons for fighting with 

 their fellow males. If we suppose, for argument, that a stag 

 absolutely devoid of the highly specialised cranial armature 

 which distinguished his fellows should strive to take and hold 

 a harem against these antlered rivals, how, on the theory, should 

 we estimate his chances of success ? There is but one possible 

 answer to such a question consistent with the hypothesis, and 

 we know that Darwin gave it; yet the fact, though the great 

 naturalist was unaware of it,* is just the other way. "Bald" 

 stags without antlers, but otherwise perfectly vigorous, probably 

 cases of atavism, are of constant occurrence among the wild 

 Red-deer of North Britain. Though wielding no weapon and 

 displaying no ornament they prove to be in all respects a match 

 for their armed and (theoretically) more attractive rivals, are 



* Mr. McNeill, of Colonsay, to whom Darwin applied for information 

 about the combats of Ked-deer, can hardly have been unaware of a fact 

 which is of constant occurrence in the Island of Jura, where his experience 

 of Red-deer was gained ; but he was evidently unaware of its significance 

 to the theory of the great naturalist. 



