"The digestive and circulatory systems are the only parts of the organization essential to life that are known to investigators; but recently I have been led to believe that I have discovered the _nervous system_, or at least a part of it, and that too in the very region of the body where there is the most activity, and therefore more likely than elsewhere to have this system most strongly developed. Immediately within the edge of the disk (_bell_) there runs all around a narrow faint band, which lies so close to the surface that it is difficult to determine precisely that it is not actually superficial. From this band there arise, at nearly equal distances all round, about a dozen excessively faint thin stripes, which converge in a general direction toward the mouth."[30] [30] Clark, _Mind in Nature_, pp. 64, 65. This band Professor Clark very correctly, as I believe, assumes to be a part of Stentor's nervous system; for, with a medium high-power lens (×500) I have been able to make out ganglionic enlargements both in the circular band and in the stripes. These ganglia are the brain of this infusorian. When the animalcule is stained with eosin, the nervous system can very readily be made out and followed throughout all of its ramifications. On one occasion, while I was studying the contractile vesicle (heart) of one of these animalcules, I saw it evince what seemed to me to be unquestionable evidences of conscious determination. Just above the creature, which was resting in its tube (it builds a gelatinous tube into which it shrinks when alarmed or disturbed in any way), there was a bit of alga, from which ripened spores were being given off. Some of these spores were ruptured (probably by my manipulations) and starch grains were escaping therefrom. The Stentor, from its location below the alga, could not reach the starch grains without altering its position. I saw it elevate itself in its tube until it touched the starch grains with its cilia. With these it swept a grain into its mouth, and then sank down in its tube. I thought, at first, that this was the result of accident, but when the creature again elevated itself, and again captured a starch grain, I was compelled to admit design! By some sense, it had discovered the presence of starch, which it recognized to be food; it could not get at this food without making a change in its position, which, therefore, it immediately proceeded to do!