Let us now consider one or two cases of instinctive behaviour which would fall under Romanes’s category of instincts of blended origin partly due to natural selection, partly to the inheritance of acquired habit. It is the custom of the house martin to build beneath the eaves. Forsaking the ancestral rocky haunts, it has been led to utilize the houses that man has built. This has all the appearance of being due to an intelligent modification of the ancestral instinct; but how far the modification has become through heredity a congenital variation, we do not know. The intelligence which is said to have enabled the martin of the past to adopt this method of nidification is still operative. The nestlings brought up under the eaves would have opportunities for acquiring experience which might lead them to build under similar circumstances. Nest and eaves would be associated in the conscious situation. Nor would the effects of natural selection be necessarily excluded. One may suppose that in the open country, far from rock-shelters, those martins in which there was a congenital tendency to build in house-shelters would bring up their broods and transmit this tendency; while those in which it was absent would either go elsewhere or fail to bring up broods at all. In the absence of fuller knowledge as to the truly instinctive nature of the behaviour, and as to its mode of genesis, we are in large degree at the mercy of conjecture. But in any case the incidence of elimination is not necessarily excluded, and there are, therefore, no grounds for denying that natural selection has been a co-operating factor in the evolution of the instinctive behaviour, if such it be. It is well known that the lapwing will apparently simulate the actions of a wounded bird, with the object, as it seems, of drawing intruders away from her nest. And such tactics are not restricted to this bird, nor even to one or two species. They are common, no doubt with diversities of detail, to such different birds as grouse, pigeons, plovers, rails, avocets, ducks, pipits, buntings, and warblers. Granting that the behaviour is truly instinctive, it forms a very pretty subject for transmissionists and their critics to quarrel over. “If we seek, as an example,” the transmissionist may exclaim, “an instinct which bears the marks of its intelligent, and therefore acquired origin, this of feigning wounded provides all that we can possibly demand.” “What mode of instinctive behaviour,” the selectionist may ask, “can be adduced which is more obviously useful to the species? Is not this just the kind of procedure which natural selection, if it be a factor at all, must fix upon and perpetuate through the elimination of failures? Those birds which, through congenital variation of behaviour, acted in this way would certainly enable their offspring to escape destruction by enemies, and these would survive to perpetuate the instinct.”