HETEROGONY AND TAXONOMY 207 



bulk that the rapidly growing bone-material should branch 

 more profusely : the same phenomenon is found, e.g., in the 

 antler-like mandibles of stag-beetles (Lucanidae) and the 

 horns of other beetles (see Fig. 93). 



We thus arrive at presumptive, prima facie evidence for 

 the truth of Ritchie's view. Finally comes experiment, and 

 settles the question. During the last hundred years, a number 

 of Red deer from Scotland (and elsewhere) have been imported 

 into New Zealand and there liberated. The regions where 

 they were liberated were profusely forest-covered ; and the 

 stags of Scottish strain in this new environment attained 

 body-weights of 200 kg. and over, with relatively large antlers 

 showing twenty and more points : in other words, they bridged 

 most of the differences between the Scottish and Carpathian 

 strains in one generation. Still further evidence is provided 

 by later events. Lacking natural enemies, the herds of deer 

 in New Zealand became too numerous, and began to destroy 

 the forests ; with overcrowding and less favourable food 

 conditions, ' degeneration ' set in, and now in many regions 

 the mean and the maximum body-weight and point-number 

 are far below what they were a few decades back. See Thomson 

 (1922) and Huxley (1931A). 



We are thus perfectly justified in concluding (1) that the 

 bulk of the observable differences in size and proportions 

 between the existing Scottish strain of Red deer and (a) the 

 existing Carpathian strain and (b) the sub-fossil Scottish type 

 are non-genetic and of no taxonomic significance. (2) However, 

 we must admit that killing of the finest males is likely to have 

 had some genetic effect ; this will have been exerted on both 

 strains, but may have been more intensive in Scotland. In 

 any case, its primary effect will have been to reduce the mean 

 size of both races, the effect on relative antler-size and point- 

 number being consequential. It should further have had a 

 ' dysgenic ' selective effect, in that among stags of equal body- 

 weight, more of those with genetic tendency to relatively 

 larger antlers will on the average have been killed off. (3) 

 There may also be true genetic differences between the Scottish 

 and Carpathian strains. But (4) the differences due to (2) and 

 (3) are relatively small, and the whole problem must be studied 

 afresh before we can be sure what they are, and indeed, as 

 regards those under (3), whether they exist at all. As corol- 

 lary, we may take it that differences in proportional antler- 

 size in dwarf island races of deer are probably only secondary 



