TRANSFORMISM 263 



The dissatisfaction of an urge leads to modification of behaviour^ 

 via the method of trial and error. Clearly any behaviouristic 

 process has a pattern, but the pattern varies. Further, the 

 mechanism of limbs, muscles, nerves, nervous centres and sense- 

 organs is capable of acting in a variety of patterns (walking, 

 running, leaping, swimming in mammals). The pattern is 

 surrounded by a fringe of random activities. This degree of 

 randomness is the opportunity for the formation of new patterns, 

 or variants of the existing one. Some such variant is tried and is 

 found not to satisfy the urge, is tried again and is found to give 

 satisfaction. Thus a new habit is formed, is found to be successful 

 and is retained by conscious or unconscious memory, or motor 

 habit, or by the survival of a neurone-path from several that have 

 been tried. 



The new habit reacts on functioning and structure. Or rather 

 variants of functioning and structure express the new habit. 

 Speaking has led to the establishment of a unilateral cerebral 

 speech-centre ; right-handedness has led to a strong development 

 of muscles and muscle-scars on the right shoulder and arm ; 

 increased bodily exercise leads to more vigorous action of the 

 heart and so to greater development of the heart-muscle ; and so 

 on. Conversely the disuse of bodily parts leads to their reductions 

 in activity and size, and perhaps to atrophy or disappearance. 

 Thus it is just as '' reasonable " to argue a priori that blindness 

 of animals that live habitually in the dark follows from the disuse 

 of eyes as to argue that such blindness is the result of natural 

 selection. Or it is equally plausible to conclude that wingless 

 insects on oceanic islands have come into existence from continued 

 disuse of the wings as to conclude that wingless insects in these 

 habitats are the results of the elimination of winged insects (by 

 reason of the latter being blown out to sea). 



Acquired processes become habitual ones in individuals. There 

 is no reason to doubt this conclusion since ordinary observation 

 and deliberated experiments demonstrate it. In some animals 

 habits are easily acquired, both by training and spontaneously, 

 and such habits persist. In ourselves habits are continually being 

 " formed," while skilled activities involving the muscle-brain- 

 sensory system are acquired as the results of imitation and training. 

 Such processes are carried out at first to the accompaniment of 

 acute consciousness and they may be clumsily effected. But what 



