AMEBOID MOVEMENT 139 



without effect, for a person with one artificial leg walks quite as 

 smooth a spiral as one with two normal limbs. 7 



From these experiments on man, it follows that there is a 

 "centre" in the central nervous system which automatically coor- 

 dinates and controls movement during locomotion and, partic- 

 ularly from the point of view of this discussion, the direction 

 of locomotion when the orienting senses are not functioning. This 

 center must be very deep seated and automatic, and in so far as 

 its influencing the direction of locomotion is concerned, it is of 

 no discoverable use to man. It may be presumed to have existed 

 before the present orienting senses originated in man, for there 

 is very good evidence that horses and perhaps dogs, too, possess 

 this mechanism. For these animals, like man, tend to walk in 

 circles when lost, a peculiarity of behavior undoubtedly due to 

 the activity of this mechanism and not to stronger right or left 

 legs, etc., as has often been suggested (e. g., Thompson, '17, p. 

 498). According to the accounts of experienced hunters, rabbits 

 also run in circles when hard pressed by hounds, which may 

 possibly be due to the suppression of the functioning of the 

 orienting senses by fear, thus allowing the automatic directing 

 mechanism to operate. 



The facts are therefore that all organisms without orienting 

 senses or equilibrating organs, or animals possessing such organs 

 which are rendered ineffective by some means, will not move in 

 straight paths nor in any kind of irregular path, but in orderly 

 paths, so that a given segment of the path serves as a basis for 

 predicting the further direction of the path. And the degree of 

 accuracy to which such prediction may attain is proportional to 

 the extent to which the activity of the automatic regulating 

 mechanism may be kept free from outside interference. The 



7 It should be added here that since this paragraph was written I have 

 been very fortunate to secure numerous records of paths swam by blind- 

 folded swimmers, which strikingly resemble those of persons walking 

 blindfolded as described above. Most of the common swimming strokes 

 were employed in these observations and occasionally several strokes were 

 employed in a single experiment. In a few cases the spiral path was 

 made up of over twenty turns, and in one case of over fifty turns. A 

 fuller discussion of these results does not seem pertinent here, and must 

 be deferred to a later date. 



