INSTINCT AND INTELLIGENCE. 591 



Of the actions which organisms perform in order to accomplish a 

 purpose, some, like those to which I have called your attention, are to 

 be placed above, others below instinct. Many of the actions of plants, 

 such as turning the leaves toward the light, the tendency of the roots 

 to grow downward, and. the closure of the flowers at night, remotely 

 resemble instinctive actions. In some the resemblance is more per- 

 fect the groping of tendrils for support, for instance. Prof. Gray 

 gives the following account of this action : " When a twining stem 

 overtops its support, the lengthening shoot is seen thrown over to one 

 side, and usually outstretched. One might suppose that it had fallen 

 over by its weight, but it is not generally so. If turned over, sa-y to 

 the north, when first observed, it will probably be found reclining to 

 the south an hour or two later, and, an hour later again, turned north- 

 ward : that is, the end of the stem sweeps round in a circle con- 

 tinually like the hand of a clock. It keeps on growing as it revolves ; 

 but the revolving has nothing to do with the growth, and indeed is 

 often so rapid that several complete turns may be made before any 

 increase in length could be observed. The time of revolving varies 

 in different species. It also depends upon the weather being slow or 

 imperceptible when it is cold, and more rapid when it is warmer. 

 Sometimes it stops when everything seems favorable, and starts again 

 after a while. The hop, bean, and morning-glory, ai'e as quick as any. 

 In a sultry day, and when in full vigor, they commonly sweep round 

 the circle in less than two hours. They move by night as well as by 

 day. This sweeping is the cause of the twining. The stem sweeps 

 round in order that it may reach some neighboring support ; as it 

 grows it sweeps a wider and wider space, that is, reaches farther and 

 farther out. When it strikes against any solid body, like the stalk 

 of a neighboring plant, it is stopped ; but the portion beyond the con- 

 tact is free to move as before, and, continuing to move on and to 

 lengthen, it necessarily winds itself round the support, that is, twines." 

 The sudden closure of the leaf of the Venus's-flytrap, as soon as it is 

 touched by an insect, and the excitement of the glandular hairs upon 

 its surface, still more closely resemble the instinctive actions of ani- 

 mals, and we here find the power to distinguish between different 

 foreign bodies, for Darwin has shown that, although the leaf will close 

 upon a small piece of meat, it is not excited by contact with a small 

 piece of glass. In animals we meet with a large class of what are 

 called reflex or automatic actions, and these are perhaps a little 

 nearer to true instinctive actions than most of those performed by 

 plants. Such are the actions of the various organs concerned in di- 

 gestion, which are passive until the presence of food calls them into 

 action, when they at once begin their work. A little higher are those 

 actions which may be performed or controlled by volition, although 

 they are usually automatic ; such as winking to protect the eye from 

 injury, and the act of throwing out the arms when in danger of fall- 



