and catch at all objects indiscriminately with their claws to try and climb. They look into each other’s eyes as if trying to discover the expression of sentiments and ideas. This may proceed from astonishment and curiosity, and the delight of the ever new impressions which the movement of the eyes cannot fail to produce in them. But must it not also be partly the result of an hereditary predisposition of their organisation, which leads them to seek in the eyes for the meaning which they express? We know that adult animals, as well as man, are endowed with this tendency which proceeds from instinct rather than individual experience.
Partly from imitation of their mother and sister, partly from the teaching of their instinct, they went off one day to a certain out-of-the-way spot, where was placed a pan full of ashes, the object of which does not require to be explained. Observing this, I carried them from time to time to this pan. The smell proceeding from it was in itself sufficient to excite them to satisfy their needs. Three or four such experiences sufficed to associate with the idea of this smell the idea of the pan, of the place where it was, and of the need to be satisfied. I do not say that this habit of cleanliness, so quickly acquired, may not as quickly be lost, by means of new associations
