296 DR. H. GADOW ON EVOLUTION [Mar. 20, 



the still somewhat imbricating shajae of the granules of the skin. 

 If it were harmful it would be disallowed, if useful it might be 

 encouraged ; but if it be 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 un- 

 important 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. We 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 A^alley, 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. How 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 

 poi'es, 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 oflspring 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, perhaj^s 

 actually 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 diflerence between 20 and 21 pores: 

 but this same difference is equally irrelevant in affecting the 



