MARSH WARBLER
feature may quite well escape our attention, a feature so small perhaps as to be beyond our powers of observation, but nevertheless sufficiently great to suggest a different meaning to the more delicate perceptual powers of a bird. We must, therefore, make due allowance for our own imperfections in this respect. Professor Lloyd Morgan suggests to me that the motor reactions may be only generically similar, that even they, as such, may very likely be specifically differentiated, and that the total complex of the emotional situation, involving factors so many and so varied, may be yet more markedly and distinctly differentiated. He sees no reason why a generic motor expression, supplemented by allied organic sensations, and qualified in experience by the total meaning of adaptive behaviour, should not be differentiated in different situations—the mating situation and the fighting situation—so as to bear its part with a difference in both. This of course is quite possible, but unsafe as it may therefore be to speak of specific similarity, I am nevertheless inclined to think that I have observed it on more than one occasion and in more than one situation. The emotional behaviour is most intense during sexual activity and while the young require the care and attention of their parents. The intermediate time is occupied almost wholly by incubation, and though this is a time of comparative quietude, yet even then there are frequent exhibitions of a similar behaviour, which, however, never reach a similar degree of intensity. Such exhibitions may occur at the assemblies of the males, when a territory is intruded upon by a neighbouring individual of the same or another species, or when a Cuckoo or some predatory bird approaches the locality in which the nest is situated. But for our present purpose we may disregard the minor exhibitions and compare those two in which the motor reactions are observed to be most in evidence. In the life-history of the Lesser Whitethroat this similarity has already been touched upon. I there stated that both the Whitethroat and Lesser Whitethroat, when anxious about their young, behaved in a
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