Intelligence as the plasticity of instinct: George J. Romanes and Darwin's earthworms

In the following article I provide a brief analysis of George J. Romanes' conception of intelligence and its relationship with instincts. Through a careful reading of some key-passages from Mental Evolution in Animals (1883)--Romanes' chief work on the subject--I endeavour to show how the very notion of intelligence was related, in Romanes' thought, to individual adaptation to the environmental novelty. Also, I attempt to clarify in what sense, according to Romanes, this capacity was to be included among the factors of organic evolution. Lastly, I compare Romanes' view with that expressed in Darwin's last book, i.e. The Formation of Vegetable Mould through the Action of Worms (1881). I contend that the two scientists basically shared the same conception of the relationship between instincts and intelligence, which accounted not only for the need of phylogenetic continuity, but also for that of discontinuity due to adaptive divergence.