Page:Popular Science Monthly Volume 25.djvu/820

802 of the lower animals when mesmerized: in these the phenomena, as far as at present observed, are much simpler than they are in man. If a frog be turned over on its back, it at once regains its normal position; if, however, it be prevented from doing so, and its struggles are for a short time gently suppressed, it becomes hypnotized. Then, although it be left at liberty to regain its normal position, it will not attempt to do so. Apart from the movements it makes in breathing, it lies motionless. If it has been held for a short time only, the hypnotic state does not last long, usually from one to five or ten minutes; but, if the movements it makes, say, at the end of one minute, or of five minutes, and so on, are suppressed, it will not infrequently happen that the frog will then stay without further movement for a considerable time, sometimes even for many hours. During the first part of this time a slight pinch, a sudden flash of light, or a loud noise, will usually cause it to turn over and sit up in its normal manner. For a moment or two it looks a little dull and confused, but rapidly regains its normal activity. During the latter part of this time it responds less and less to external stimuli. When it is in this state, it may be propped up against a support with its legs crossed under it, or placed so that it rests on its head, or placed on its side with its legs arranged in this or that fashion, without offering the least resistance.

I have spoken of the frog as being hypnotized or mesmerized. Let us consider what is meant by this. I think it is obvious that the animal does not remain passive from any astuteness on its part; it is incredible that the frog, finding its efforts to escape ineffective, should make up its mind to remain quiet, and should, although at liberty to move, stay still for hours, becoming more and more determined as time goes on to take no notice of noises, of flashes of light, and of pinching of its skin. On the contrary, it is, I think, obvious that in some way its will has become paralyzed. In order to attempt to explain how this is brought about, we must consider an aspect of reflex action which is very little understood.

A brainless frog will, when its leg is gently pinched, kick out the leg; but, if just previously some other part of the body has also been pinched, one of two opposite things may take place—the leg may be kicked out more quickly and vigorously, or it may not be kicked out at all. In both cases the nerve-center involved in producing the movement of the leg receives an additional impulse from another nerve-center, but in one case the additional impulse increases the activity of the nerve-center involved in the reflex action, in the other case it annuls this activity—there is, to use the physiological term, an inhibition of the "reflex" nerve-center.

Inhibition by impulses proceeding from the cortex of the brain occurs every day of our lives. The "will" is perpetually being brought into play to inhibit some nerve-center or other. For example, you may be on the verge of yawning, when it suddenly occurs to you that