ESSAY-REVIEWS 685 



by flight, for it makes diagonal cyclic movements of the limbs as in running away, 

 for flight under normal conditions is associated with fear ; it however also shows 

 signs of anger, for it turns its head towards the side of the injury, snarling, 

 showing its canine teeth, and howling. It may be supposed that the former 

 behaviour would be associated with the feeling of fear, the latter with anger. 

 But in the decerebrate animal the one motor reaction to injury does not appear to 

 interfere with the other ; the animal having no brain has no judgment of value 

 to make, and therefore makes no choice in its behaviour of flight and fight. If 

 one mode of behaviour interfered with the other's operation, in all probability the 

 less effective would cease. The following experiment supports this conclusion. 

 In the spinal dog, that is an animal with the spinal cord severed high up, 

 Sherrington has shown that a conflict takes place between the scratch reflex and 

 the reflex to pain, in which the latter prevails. To produce the scratch reflex, an 

 excitation of the hair in the forepart of the body is produced, similar to that 

 caused by a parasite ; this causes the hind limb on that side to be drawn up to 

 scratch the part irritated. All the while the rhythmical movements of the hind 

 leg are taking place, the animal is supporting itself on three legs. Now if the 

 pain reflex of withdrawal from injury by a sharp prick (such as a thorn would 

 cause), is excited in the other resting hind foot, the scratch reflex immediately 

 ceases, in order that one hind leg can rest on the ground, thus allowing the 

 injured hind limb to be drawn up. There is a choice here and a mechanism of 

 unconscious judgment of value in the protective reflexes. Mr. Shand cites fear 

 as the emotional system containing several instincts ; thus there is the instinct of 

 concealment, the instinct of flight, and even the instinct of fight when the other 

 two are impossible. Mr. McDougall contests this view, and says that flight and 

 concealment are one instinct, for flight has the same end, namely, concealment ; 

 but from a physiological standpoint they are different. Concealment may be 

 effected by immobility, in which case there is a distinct diminution of liberation of 

 muscular energy, and concealment by immobility from a physiological point of 

 view is surely not the same instinct as the extraordinary liberation of energy 

 required to escape pursuit successfully. 



Here again I do not think psychologists have given sufficient attention to 

 physiological experiments. We may assume that the perception of danger arouses 

 the emotion of fear, and of fright (extreme fear), which acts on the vaso-motor 

 centre, inhibiting its action and causing a depressor effect, so that the large 

 internal arteries are dilated, and the blood flowing away from the skin and 

 muscles causes coldness and pallor of the skin with erection of hairs ; the 

 muscles lose their tone and are deprived of energy to contract. This paralysis 

 of fear leads to insensibility which under favourable conditions might lead to 

 concealment, but certainly could not lead to successful flight and concealment. 

 For successful flight requires the same conditions for the production and liberation 

 of muscular energy as fight, and an animal may acquire by experience a conscious 

 judgment of value between flight and fight that under certain conditions it 

 exercises to its advantage. 



Nature has provided a remedy to this paralysing effect of fear independent of 

 the will and consciousness, but probably not independent of the feeling of fear ; 

 it is the provision of a bio-chemical stimulus to the whole sympathetic nervous 

 system and plain muscle fibre. Elliott and Cannon have shown experimentally 

 that when an animal is frightened a stimulus passes down the splanchnic nerves 

 to the medullary substance of the suprarenal gland, causing an increase of adrenalin 

 to pass into the circulation ; this has a powerful vaso-constrictor effect and raises 



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