\3^ 



NATURE 



[November 26, 1914 



A PHYSIOLOGICAL PUZZLE.^ 



WHAT the magicians did in ancient days 

 before Pharaoh in the way of turning 

 sticks into snakes has often been done since, or 

 its converse of turning snake into stick, but it 

 remains in great measure a physiological puzzle. 

 If the cobra in its threatening attitude be deftly- 

 caught behind the head and gently pressed, it soon 

 becomes stiff, and will remain so for a consider- 

 able time, either coiled up or drawn out straight. 

 It has passed into the strange state of animal 

 hypnosis. In 1646 the Jesuit father, Athanasius 

 Kircher, described the famous experiment, "de 

 imaginatione gallinae. " He laid a hen on the 

 table, held it firmly for a little, and drew a chalk 

 line in front of its eyes, with the result that it 

 remained as if in katalepsy. Czermak showed 

 in 1872—3 that this could be done with many 

 birds, and that the chalk line was quite unneces- 

 sary. The veteran entomologist, Fabre, tells us 

 that he and his school companions used to put a 

 whole flock of turkeys to sleep with their heads 

 tucked under their wings. Animal hypnosis can 

 also be induced in mammals (guinea-pig, rabbit, 

 mouse, squirrel, bat, dog, cat), and this is usually 

 effected experimentally by fastening them to a 

 board and turning this suddenly upside down. 

 Frogs are readily susceptible, and newts will 

 also submit. 



In backboned animals the state of immobility 

 is scarcely known except in artificial conditions, 

 and can scarcely be of much importance in life. 

 It is otherwise, however, when we pass to the 

 analogous " death-feigning " or katalepsy in cer- 

 tain beetles, water bugs, stick-insects, and 

 spiders. The immobility occurs in natural con- 

 ditions, and it seems often to save the life. The 

 case of the female Galeodes is of special interest, 

 since the more than recalcitrant female passes 

 into a convenient hypnosis when she is suddenly 

 seized by the weaker male. This may be induced 

 artificially in the sexually mature female by 

 gripping her suddenly in the dorsal region of the 

 abdomen with a pair of fine forceps and raising 

 her from the ground. She remains quite passive 

 until she is restored to earth. It is very interest- 

 ing to note that older females, who have paired, 

 do not pass into katalepsy, but turn fiercely on the 

 forceps. In the same connection it is worth 

 recalling that when we lift a shore-crab, holding 

 the shield between finger and thumb, and wave it 

 in the air, it becomes immobile, but the two 

 sexes dispose their limbs in different ways, the 

 female bending them in over the abdomen, as if 

 protecting the eggs. The familiar case of the 

 fresh-water crayfish is interesting, because the 

 creature does not pass suddenly into hypnosis, but 

 usually resists for a considerable time. It may 

 be fixed in any position of equilibrium — on its 

 head, on its back, or even in its normal pose. The 

 stick-insect, Dixippus, which feeds at night, 

 normally assumes its protective immobile attitude 



1 " Hvpnose und Katalepsie bei Tieren im Vergleich zur menschlichen 

 Hypnose." By F.rnst Mangold. Pp. 82 + iB figs. (Jena: Fischer, 1914)- 

 Price 2.50 marks. 



NO. 2352, VOL. 94] 



under the stimulus of light, but a mechanical 

 stimulus also serves. Schmidt has recently shown 

 that the insect can be fixed in any grotesque 

 attitude for hours on end. It has been shown that 

 the transition from one state to the other can 

 in this creature be effected almost in a moment. 

 In a case like the stick-insect we cannot but 

 regard the kataleptic habit as of protective value ; 

 it adds to the safety which the protective form 

 and the protective colour also help to secure. 

 The creature behaves as if it knew, for it almost 

 always disposes itself parallel to the twig to 

 which it is attached. Schleip also points out that 

 when it lets go on being touched, the elongated, 

 straight disposition of the appendages makes it 

 easier for it to slip down among the twigs. In 

 Galeodes, as we have noted, the sudden passivity 

 of the female is of importance in reproduction, 

 and a similar phenomenon has been observed in 

 the female octopus. In many cases, however, it 

 seems quite impossible to maintain that the kata- 

 lepsy is protective at all. Thus Fabre notes that 

 Scaritcs bupariiis, one of the large ground-beetles, 

 which a shake sends into a lasting katalepsy, is 

 voracious, well-armoured, nocturnal, and unpalat- 

 able. What has it to do with "death-feigning"? 

 Cases of this sort suggest that the kataleptic 

 tendency may be simply a concomitant of a certain 

 type of nervous constitution, and that it is only 

 occasionally turned to advantage. 



According to Mangold, the characteristics of 

 human hypnosis are : that it is a sleep-like state, 

 induced by suggestion ; that it implies a rapport 

 between the hypnotiser and the patient, and an 

 increased amenability to suggestion ; that it in- 

 volves an inhibited power of locomotion and of 

 "righting" the body, a change in muscular tonus 

 — from initial increase to somewhat sudden de- 

 crease — and a change in sensitiveness which may 

 amount to anaesthesia and analgesia. Suggestion 

 is a psvchically-conditioned effect, for which the 

 physiological stimulus seems to be inadequate. 

 Little is known in regard to the hypnosis of the 

 highest animals, like dogs and cats, the amen- 

 abilitv of which to human influence is well known, 

 but in ordinary cases it may be concluded, accord- 

 ing to Mangold, that animal hypnosis differs from 

 man's in the absence of the suggestion, the 

 rapport, and the deeper stages. It may be in- 

 duced in animals without a cerebrum, which 

 indicates that the psychological factor is unim- 

 portant. Physiologically considered, however, 

 the more typical forms of animal hypnosis must 

 be ranked beside human hypnosis, and studied in 

 this light. 



The resemblances are many. The sleep-like 

 state is induced in man by suggestion or psychical 

 inhibition, in animals by mechanical inhibition, 

 but in both cases sensory stimuli may assist. 

 These stimuli may be optic (fixing the gaze on 

 some object), or tactile (stroking the skin), or 

 otherwise. Sometimes an absence of wonted 

 stimuli may induce the state, as in the case 

 of absolute silence. The awakening may be 

 brought about by sounds, shaking, currents 



