BIOPSYCHOLOGICAL 643 



big-brained" types, the inheritance is mainly the free, nimble, 

 oducable, intelligent MiND-body increasingly dominating mere Body- 

 mind, while among "little-brained" types the inheritance is mainly 

 a stereotyped series of reactions — of BoDY-mind with very little of 

 mind in it. 



15. Along the line which we may call the power of initiative and 

 experiment, there is not only intelligent behaviour (rising to rational 

 conduct in Man) ; there is the tentative plasticity of some humble 

 animals like starfishes, where the absence of any definite nerve- 

 centres forbids the use of any term like intelligence. 



16. Along the line which we may call the capacity for enregistra- 

 tion, there is not only instinctive behaviour (at diverse levels); 

 there are obligatory movements or tropisms, as when the elvers 

 swim persistently upstream ; there are engrained rhythms, as when 

 the Convoluta worms come to the surface of the sand when the tide 

 goes out, and retreat again at the first splash of the flowing wave; 

 there are reflex actions, simple and complex, as when the earthworm 

 jerks back into its burrow, or the nestling opens its mouth and 

 swallows when its beak is touched by the food which the but dimly 

 sensed parent brings. 



17. These two lines of animal behaviour have their respective 

 advantages and disadvantages. Thus what is enregistered is ready 

 made, and it is usually quick and sure. Yet it is non-plastic and 

 often wooden. The power of initiative is plastic ; it can face change, 

 it offers alternatives, it opens the door to choice. Yet it requires 

 apprenticeship. 



18. The two lines intersect when an animal at a juncture tries its 

 repertory of enregistered reactions until perhaps it gets an effective 

 answer. A trial- and- error method is very common at diverse levels; 

 and it may be either a trying of engrained capacities or a making 

 of novel tentatives. If only one pre-established answer-back be 

 given, and that is effective, the enregistration type of behaviour is 

 illustrated; if the answer-back is novel, the initiative type of be- 

 haviour is illustrated ; if there is a trying of one engrained reaction 

 after another, the two lines intersect. 



19. If we picture an ostrich feather held in the left hand sloping 

 gently upwards, with the convex surface up and the concave surface 

 down, and with one set of barbs directed upwards and the other set 

 directed downwards, then we have a useful diagram of the diversity 

 of animal behaviour. The upturned barbs will represent the various 

 modes of initiative, tentative, experimental behaviour, culminating 

 in the high inteUigence of horse and dog. The down-turned barbs 

 will represent the various modes of enregistered, engrained, reflex 

 behaviour, culminating in the marvellous instincts of ants and bees. 

 The convex outer surface of the whole and of each part may typify 

 the bodily, the nervous, the physiological, the objective. The 



