Library

Notes: Summary Results 1. Specimens of the millipede Schizophyllum which run on a straight course under dim red illumination were led into a narrow alleyway, about twice their width and more than twice their length. The alleyway was straight except for a bend midway (the angle of bend could be varied). When the millipeds left the alleyway they made a turn of about the same angular size as that of the bend forced upon them, but in the opposite direction, thus they resumed roughly their original bearing. The relation between the amount of alleyway-bend and compensatory turn is non-linear. Such a compensatory turn can also be induced by optical means, i.e. by replacing the alleyway by a bent shadowy path on an otherwise brightly illuminated surface. li]2.|A single sharp bend has the same effect as many small ones, even of various directions, and the effect is independent of the length of the intervals (that is, whether longer or shorter than the animal) provided the net total of angular amount is the same. li]3.|The size of the compensatory turn is proportional to the number of the millipede's segments that have passed the bend; e.g. it is decreased to 1/2, if only 1/2 of the millipede has passed it. li]4.|If, after some forward portion of the animal has completed a compensatory turn, the rear segments are prevented from doing so by quickly lining them up with the front end, the front immediately begins an additional turn in the same direction as the first one. The amount of the turn increases with the number of segments that were prevented from turning. This additional turn can be „postponed“ by having the front end creep into a straight alleyway before the line-up. li]5.|If, after the animal has completely passed the bend, but not yet reached the end of the alleyway, a forward portion is passively pushed into the expected direction of the compensatory bearing, no turning occurs until the animal is completely out of the alleyway. Then it immediately turns about an angle proportional to the number of segments that were prevented from compensating. li]6.|If the animal is dragged passively, head first, through a bent alleyway, a compensatory turn is initiated as soon as the millipede resumes locomotion. The amount of the turn is inversely proportional to the speed of the dragging. If the animal is dragged rear end first, however, no compensatory turn ensues. li]7.|An active compensatory run can he experimentally substituted for by passively dragging the animal, rear or front end first, through a corresponding bend instead, i.e. the millipede runs straight after such a procedure. The result is independent of the speed of the drag. li]8.|If, after just having actively passed a bend, the animal is induced to run actively backwards through the same bend, no turn occurs.