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Show 892 SIR y. BROOKE ON THE [Nov. 19, hensive fact of the gradual augmentation of complexity in these organs through geological time; but as the converse, namely the existence of highly complicated antlers in the Miocene and Pliocene periods, finds no support in the Geological record, the simple antlers of some existing species may be, I think, safely regarded as the result of arrestation, dependent on a less severe struggle for existence, or possibly upon some hitherto undiscovered influence. (2) A constant tendency to vary. Of this, any one can satisfy himself by the inspection of large collections of antlers. No two antlers are ever exactly alike ; and the variations to which the antlers are subject in some species (e. g. Cervus elaphus, vide infr. p. 910) is so great, that in the absence of a large series they would be held as indicative of several distinct species. (3) Variation extending far enough to induce the partial atrophy of one part of the antler to compensate for the extra development of some other part. To illustrate this subject exhaustively would occupy more space than can be well devoted to it in the present paper. An attentive examination of any large collection will yield abundant evidence that such is invariably the case. It will, perhaps, be sufficient for my present purpose to bring forward one special example. The normal form of the upper half of the antlers of the common Fallow Deer (fig. 9, p. 914) may be described as broadly palmated, with several rudimentary tines produced from the posterior margin of the palm, the tine situated lowest on the palm exceeding the others slightly in length (fig. 9, d). In my cousin Mr. J. Bloomfield's place, Castle Caldwell, on the shores of Lough Erne, there is a herd of Fallow Deer which have lived at large in the woods, and under perfectly natural conditions, for upwards of 50 years. The antlers of these Deer are so remarkable in form, and present the peculiarities in which they are remarkable so constantly, that they could be recognized amongst a large collection of Fallow-Deers' antlers without the slightest difficulty. The tine growing from the inferior and posterior border of the palm (Plate LV. fig. 3, d) is in the Castle-Cald-well Deer immensely developed, and the palm itself is much contracted and seldom bears more than 3 or 4 tines. Variation is still actively at work on the antlers of these Deer, and reversion towards the normal form occasionally asserts itself; but, notwithstanding, a fixed type of antler has stamped itself indelibly upon the males in this herd in the short space of 50 years, and the peculiarities characteristic of that type are unquestionably the result of the extra development of one of the posterior tines and the consequent partial atrophy of the palm. (4) The transmission and fixation of such variations by heredity. That this is the case has been in a large measure proved by what has been already said; but the following fact places the matter beyond all possibility of doubt. The Castle-Caldwell Deer are the descendants of about one or two males and twice as many females. A single antler of one of the fathers of the herd has been fortunately preserved in the Museum at Castle Caldwell. This antler (Plate |
