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 May, I9O 7 ORNITHOLOGY FOR A STUDENT OF EVOLUTIONARY PROBLEMS I close with a single reflection on the outlook of biological generalization of the day. At uo time during the last twenty-five years have evolution hypotheses beeu so up in the air as just now. A few writers believe that the idea of evolution itself is going to sinash. Sober, well-balanced naturalists are not skeptical to this extent. Many of them are, however, disposed. to settle down to the view that search after a method by which species originate is time wasted simply because there is no such a thiug. There are many factors, they say, in evolution, and biology has done all incumbent upon it when it has found out what they are. Cer- tain it is now that there are various factors in species production, and it is a great achievement to have unearthed so many of them. Natural selection is a widely operative factor; so is sexual selection; so is orthogenesis; so is isolation; so, quite certainly, is mutation. The list, were it complete, of more or less distinct, more or less efficient, factors would be much longer. I ask are we to rest here? Having corralled these?)c[o's, are we going to write.$'/s over the gate of the corral? Not if biological motive is true to itself. Does uot your mind and mine, and every mind that is in the habit of thinking at all, 'start off immediately and unrestraiu- ably, the last factor having been lodged in the corral, in quest of some one or at least a less uumber of factors or principles underlying those already captured? If species are fully produced by so many differeut causes, different combinations of these operating together in different groups of plants and animals, how do we know that species have anything in common? Is it a tenet of biology or any other physical or spiritual science that unlike causes produce like results? And if yon are not certaiu that all species have something in common, what justification have you in attempting to treat theIn all alike in classification ? What is the good of bothering about uniform rules of nomenclature if the rules are to apply to differ- entthings? But are we uot warranted iu believing, nay, are we ot compelled by the totality of biological data to believe that there is more uuity iu evolution than all these factors indicate? Is there not fundamentality in the metabolic processes of organisms? Is not this true also of response to stimulus? Is it not true of re- production ? Has not the cellular theory of organization a uuifyiug principle in it that is about the securest of all biological generalizations ? It is, I ant confident, only statiug what every thoughtful naturalist assents to without hesitation to say that the goal of biology--uot a remote, but the immediate, animating goal--is greater unificatiou of its knowledge. Minds can never rest from the search for deeper, more inclusive principles. This brings our evening's discussion to a close at the point from which it started. ,Sdz'ersily o?' (d/}rda, Z]erd'elcy, THE BIRD ISLANDS OF SOUTH AFRICA By W. L. SCLATER M. B. O. U. NE of the most remarkable forms of bird life at present existing is certainly the group of Penguins. These birds, which constitute the Order hn- pennes, stand wide apart from all the'other living Orders of birds not only iu their structure but also in their life history and distribution. They are the only birds in which the metatarsal bones of the adult show plainly their threefold origin, the bones in question being short and separated by deep grooves. The lr' The pellng and capitalization iu th article acco;t With the request of the author. ---