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Show 296 DR. II. GADOW ON EVOLUTION [Mar. 20, the still somewhat imbricating shape of the granules of the skin. If it were harmful it would be disallowed, if useful it might be encouraged ; but if it he neither, it would still continue until it disappears by itself, when the granules have become too uniform for this accidental by-play. Almost every one of the taxonomic characters investigated in this paper has an amplitude of variation within some of the species which equals that of the whole genus. From this fact we can draw several conclusions. Either these variations are unimportant to the welfare of that particular species, or this is still in an unsettled condition, i. e. it is making new species. If the exceptional or extreme variations were harmful, we should expect them to have been eradicated long ago; even the tendency of varying in that particular direction, unless this kind of variation is of comparatively recent date. Again, since they occur in individuals of the same locality, they have obviously not been swamped by panmixis. All these Cnemidophori form practically isolated clans, since they do not travel. W e might say that the inhabitants of a plain have more chances of mixing, and that therefore they are more monotonous in their features, have in fact arrived at the general average. Clans on the other hand confined in a valley, or on a mountain, or in intricate terrain, are isolated, and they should therefore be still more subject to panmixis. But instead of their having settled down to fixed monotony, we find just the reverse: the variations of their characters are at their liveliest. H O W T are these facts to be reconciled ? Only, I venture to submit, by the assumption that these variations are the direct result of, caused by, the direct influence of the surroundings, regardless of natural selection. which can, and will, step in only when certain variations turn out to be harmful in that particular locality. It may mean an improvement to have 21 instead of 20 femoral pores, instead of increasing the work of each pore by 5 per cent.; but if that 21-pored lizard should mate with an old-fashioned 18- pored female, the offspring may probably show some gain in comparison with the mother. Whatever may be the use of these pores, their activity certainly depends upon the requirements of the whole organism of the lizard, which in turn is influenced by the conditions under which it happens to live. If that place favours, in the most, roundabout way, the activity of these pores, they will react by increase, either in size or in numbers, perhaps Medially thus increasing during the life of one individual. Not all individuals respond alike easily. Some lag behind, and may be they come thereby to grief, although this is not very likely. Take the present case. What puts an end to the refractory lizard are the snakes, the ground-cuckoo, the Croto-phaga, and similar enemies, whose attacks represent accidents absolutely regardless of the difference between 20 and 21 pores; but this same difference is equally irrelevant in affecting the |