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suddenly grasped behind the head and pressed on the back of the head when it is in the “threatening attitude” it becomes cataleptic and wax-like; it would seem (Exodus VII) that these facts were known to Aaron and to Pharaoh’s sorcerers.

In many cases these curious tricks bring no benefit that we can see to the animal in which they appear. They may be looked upon as an accidental result of the way in which its nervous system works. A sudden strange stimulus falling on the cortex will temporarily inhibit its other activitiesin more familiar words, the creature concentrates its attention to the new event. And so, as we have seen, a monotonous, meaningless stimulus is inhibitory too. Both these kinds of inhibition, normally controlled and purposive, may under artificial conditions become exaggerated and lead to complete immobilization of the organism.

But there are special cases in which the same tendency has been built upon and utilized. Variation and natural selection between them stretched the neck of the giraffe and the little finger of the pterodactyl to astonishing proportions; they seized on the accidental fact that when muscles or glands work they produce slight electric currents, and built from that the powerful batteries of the electric eel and the torpedo. So with these obscure nervous processes.

It is well known that many kinds of spiders and insects will ‘“‘sham dead” if they are alarmed, becoming stiff and motionless ; and the same thing can be seen when a speckled fawn cowers flat on the ground, or when we startle a nestling ring-plover (a bird which nests on the ground) and it flattens itself out and becomes all but invisible. Here the stimulus that frightens the creature sets up an inhibition which is allowed to sweep through the brain; as a result the creature becomes paralysed and motionless, and therefore inconspicuous.

Perhaps the most striking case of all is that of the stick-insect Dixippus morosus, which prowls about by night, but falls at once into a rigid catalepsy whenever it is illuminated. It spends the day thus hypnotized, and its stillness conspires with its admirable protective architecture to merge it with the twigs on which it lives. In this state it can be put into strange attitudes, and will hold them, just like a hypnotized man. And just as hypnosis is in ourselves a phenomenon. that happens in the highest parts of the brain, so with these insects; a Dixippus whose brain ganglion has been removed will prowl restlessly and aimlessly around, and

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never show any signs of “‘ shamming dead,” even when brightly illuminated, touched, or jarred.

Thus, under a variety of strange appearances, we trace this process of inhibitionspread. In a spider shamming dead, in the sudden stiffening and insensibility to surrounding things of a man struck by an idea, in the docility of a charmed serpent, we can see the same process at work, now as a mere curious accident and now turned to this end or that. Like the molecules of a crystallizing salt the facts arrange themselves, and the science of the mind takes form.

Naturally, Pavlov does not claim that his experiments explain all the phenomena of hypnotism. ‘They simply show how the onset of the hypnotic state can be interpreted. Such facts as suggestion, which involves the use of language, are untouched. But it is worth noting that Pavlov has put forward a theory of suggestion (although to give an account of it here would involve a deeper and more technical analysis of the fundamental properties of excitation and inhibition than we can embark upon) and declares in his latest book, ““I hope to be able to produce a phenomenon in animals analogous to ‘suggestion’ in man during hypnosis.”

Other interesting phenomena were observed while the dogs were waking up and the flood of inhibition in their brain was receding and localizing itself. There was, for example, a ‘‘ paradoxical phase,” when all the reactions of the animal seemed to be upside-down. Stimuli which usually produced very weak conditioned reflexes now acted very strongly, while stimuli which were powerful had no effect. The retreat of the inhibition was not a simple ebb: a release here meant a passing intensification there. We cannot go into details with the space at our disposal. We may, however, pause and point a moral. We have seen how the deliberately simplified conditions to which the animals were subjected led to an unusual extension of the inhibitory processes in their brains, and what peculiar results this spreading produced in several cases. Put a dog—or a man, for that matter—into a darkened room, with strange and unfamiliar and, on the whole, meaningless things going on, and heaven knows what disturbances of the normal mental balance may not take place in his hemispheres. This is a hint with various implications ; we commend it especially to amateurs in spiritualistic science.