into voluntary and automatic. As the term voluntary is misleading, the word ratiocinative has been substituted for it.
The relations of animal acts may, then, be considered as follows: Automatic acts display design for the well-being of the animal, but are invariable in their action, not changing immediately in adaptation to new or modified needs. Ratiocinative acts, on the other hand, are performed in accordance with circumstances as they arise, and are not rhythmical or invariable in their action. Their existence implies the presence of a certain development of mind, which the automatic acts do not so obviously display. Ratiocinative acts are very common in animals, as those who observe them can always testify. The automatic acts increase in relative importance as we descend the scale of being, but as they also display a general beneficial design it is not possible to draw the line between them and the ratiocinative. In fact, the one passes into the other by the well-known process which I call cryptonoÿ, as will presently be explained. If acts affect structure, it is evident, that if the acts are beneficial, the structure they produce must be so also. From what has preceded, it is also evident that the more intelligent acts will produce correspondingly more beneficial structures than the less intelligent. But since these changes are only effected by long-continued movements on the part of an animal, it is clear that an act is likely to become automatic before it can become an important cause of evolution of animal forms. The history of animal movements has probably been as follows:
Fig. 7.—Skull of Coryphodon elephantopus, two ninths natural size; a corner removed from the skull so as to display the small brain-cavity at the base, (from New Mexico.)
Protoplasm presents certain movements, of which contractility is one, which will respond to certain stimuli under proper conditions of nutrition and temperature. It may perform movements which cause a simple mass of it to change its location in a fluid medium. Such acts, however, lack the element of design, or adaptation to the needs of the
