 (iv) The fourth and last type of movement in Pereira’s theory is instinctive movements. Pereira attributed these movements to what he called natural instinct. Among the examples he used is the persecution of the mouse by the cat. Pereira recognized that the perfection and complexity of these movements are such that, if they are not carefully examined, they could lead us to the conclusion that not only do animals have sensations, but that they also possess thought and reason. However, mere appearances are not evidence or proof. For example, he described the astonishing action of semen deposited by the male inside the vulva, and yet, semen does not have sensory perception. The same can be said of nutritional processes, wherein the relationships between different organs cause a selection of some materials and the rejection of others, and neither these operations are the result of a sensory process (AM: I.343–345).