Another indication of the fact that no intelligence lies behind the instinctive behavior of brutes is manifest from their evident _unconsciousness of purpose_. That the animal is ignorant of the purpose implied in its own instinctive actions appears from the fact that it will carry out these operations with futile diligence and exactitude, even when, through accident, the purpose is conspicuously absent. Thus the hen deprived of her eggs will, nevertheless, continue the now futile process of incubation for twenty-one days, or longer, despite the fact that her obstinacy in maintaining the straw of the empty nest at a temperature of 104° F. serves no useful purpose whatever. She cannot but sense the absence of the eggs; she has not, however, the intelligence to realize that incubation without eggs is vain. The connection between the latter and the former is something that mere sense cannot apprehend. Hence the hen is not troubled by the purposelessness of her performance. Fabre gives many examples of this futile persistence in instinctive operations, despite their complete frustration. Alluding to the outcome of his experiments on the Mason-wasp _Pelapaeus_, he says: “The Mason bees, the Caterpillar of the Great Peacock Moth, and many others, when subjected to similar tests, are guilty of the same illogical behaviour: they continue, in the normal order, their series of industrious actions, though accident has now rendered them all useless. Just like millstones unable to cease revolving though there be no corn left to grind, let them once be given the compelling power and they will continue to perform their task despite its futility.” (“Bramble Bees,” pp. 192, 193.)