[[p. xxxiv]] Mr. A. R. Wallace, after some prefatory remarks, said that there were one or two points in the discussion that afternoon about which he should like to say a few words. First of all he must refer to the interesting and most remarkable specimens of ancient implements and art which Sir Antonio Brady had been good enough to show them. He [[p. xxxv]] was particularly struck with the stone spear-head so fashioned as to give the weapon a rotatory motion in the air, and thus increase the accuracy of flight. This specimen was especially interesting to him because it came from America. When he was travelling there he noticed that the arrows of the aborigines of the Amazon valley were fringed with feathers arranged spirally round the shafts so as to keep the weapon in a straight path when projected. In many other parts, as for instance in New Guinea, weapons are not so "rifled," and it was, therefore, a very noteworthy fact that the custom of rifling spears and arrows had persisted in America from the earliest stone ages until now.

     In Mr. Wallace's opinion the carved figures of men and animals which Sir Antonio Brady had exhibited were also of the very greatest interest; they were of such intense interest that it was difficult to believe they were genuine. If he remembered rightly, the animal carvings of Reindeer, Mammoth, &c., which had hitherto been discovered were all of a period supposed to be intermediate between the Palæolithic and Neolithic ages--the "Reindeer Period" of M. Lartet; but it was evident, Sir Antonio's carvings being accepted as genuine, that such were not by any means the oldest. They had represented by them not only the animals then existing, but also the men who fed upon them; of the hunter as well as the hunted. It must be remembered that savages always depicted in their carvings and drawings their own type, and therefore we may take the figures carved upon the bones to represent the type of face which prevailed among the hunters of the Mammoth. One of the carvings presented a curious resemblance to the profile of the Duke of Wellington, and accepting that as a contemporaneous carving, they might draw therefrom the conclusion that the early hunters of the Mammoth were by no means a low and degraded race. This was an exceedingly interesting point in connection with the question of the antiquity of man. We have not made the slightest approach towards the discovery of a lower type. Although we have been enabled to trace the Old World hunter back to the Pleistocene age, he remains as much man as the most intelligent races of the present day. Of course he did not mean therefore to infer that men of a lower type had not existed, but he believed that they must go immensely further back to discover the first traces of primeval man. He did not agree with Professor Boyd Dawkins in the inference that man did not exist in the Miocene age because the animals which must have surrounded him, being of forms which had developed into other species, man would have therefore been influenced by the law of development, and in the succeeding ages would have presented characters very different from the genus Homo as at present existing. Mr. Wallace was disposed to think that, man having reached a certain stage of development, his physical and mental qualities would enable him rather to control than be controlled by the changing character of his environment; and [[p. xxxvi]] therefore, although he might advance in his mind, his bodily structure would remain very constant. The fact that the earliest races of men yet traced out present a type similar to man now existing is rather a proof that the human species is immensely more ancient than we hitherto have had any conception.

     With reference to the Glacial Epoch in Geology, Mr. Wallace said it was a subject which for upwards of fifteen years he had thought and written upon. He was glad to say that he did not differ from their good friend Sir Antonio Brady to the extent he believed. He quite agreed that the period of the Mammoth and the earlier Mammalia was a period close upon or within the Glacial Epoch. In point of fact he considered that the time would come when they would find that changes in climatal conditions have been the principal causes in producing the changes of plants and animals on the earth. He believed that the chief agent in inducing these changes of climate was the geographical alterations in the contours of continents by submergence and upheaval in different stages of the earth's history. He had lately been attempting to show in some detail how it was that these changes in Geography did afford us the means of explaining that hitherto insolvable problem--the mild and luxurious vegetation of the Arctic regions during the Miocene and many earlier Geological epochs. It was quite impossible to accept in its entirety Mr. Croll's explanation; but Mr. Wallace believed he had found the solution in Mr. Croll's own theory of Ocean Currents. Mr. Croll maintained that there had been alternate mild and glacial conditions in the northern hemisphere throughout the Tertiary period; but the objection to this was that all the Geological evidence showed that before the last Glacial Epoch mild climates alone prevailed in the Arctic regions, whether in the Upper or Lower Miocene, the Cretaceous, the Jurassic or the Carboniferous period;--in fact, every Geological Formation in the Arctic Regions, anterior to the Pliocene, furnished evidence of mild, and in no single instance of cold climates. Now Mr. Croll had himself demonstrated the wonderful power of the Gulf Stream in carrying the warmth of the Tropics into North Temperate and Polar Regions. At present this was the only important body of warm water that reached the Arctic Seas, but there was good geological evidence that in earlier ages the great Northern Continents--Europe, Asia, and North America--were not as now solid masses of land, but were broken up and penetrated by arms of the sea which carried other bodies of warm water northward. When this was the case, the formation of ice in the polar seas would be entirely prevented; and when there was no ice the power of the sun during the long day of the polar summer was amply sufficient to support the vegetation, the remains of which so astonish us in the Arctic Regions. The last Glacial Epoch was undoubtedly produced by the astronomical conditions which have been so well set forth and illustrated by Mr. [[p. xxxvii]] Croll, but it was only rendered possible by the concurrence of geographical conditions, then recently brought about, by which the greater part of the warm water of the Tropics which had before entered the Polar seas was shut out from them by the elevation and solidification of the great Northern Continents. This continued growth and extension of the land in the Northern Continent during the Tertiary period has been long known to geologists, but its importance as affecting the most powerful of all climatal agencies--northward flowing and heat-bearing ocean currents--appears to have been hitherto overlooked.

     By thus modifying Mr. Croll's theory, giving greater importance to ocean currents and comparatively less to astronomical causes, Mr. Wallace believed that the difficulties that had hitherto beset all attempts to explain the mild climates of the Arctic Regions, so as to satisfy both geologists and physicists, might be overcome; and in his forthcoming work, "Island Life," he had endeavoured to demonstrate the correctness of these views. (Loud applause.)