^o^- ^] Bovard. — Coudylostoma patens. 355 



Direction of Gliding. — The direction of gliding is usually 

 forward, with occasional movements backward as seen in the 

 motor reaction. Only under extraordinary conditions is the 

 movement in a straight line, the usual course being the arc of a 

 circle whose center lies to the left of the animal. The shape of 

 the animal would cause such a direction on account of the curva- 

 ture of the body. 



Although not the normal direction, the animals may be ob- 

 served occasionally to move in circles to the right. Animals that 

 have been disturbed by moving from one aquarium to another 

 show this latter movement beautifully. By sudden jerking of 

 th" anterior end to the right they move toward that side. All 

 the movements are cjuick and erratic for a considerable time, till 

 they become accustomed to their surroundings. Gradually the 

 rapid movements slow down and the normal movement to the left 

 is observed. In other cases the whole anterior end may be bent 

 to the right (see fig. 12), but such a condition is usually of very 

 short duration. 



Direction of Movement in Cut Pieces. — The form of the body 

 of Coudylostoma determines the direction of its movement. This 

 is clearly demonstrated in the locomotion of cut pieces when the 

 animal is transected. The direction is normally to the left and 

 the posterior end of the animal is bent to the left. Is there any 

 correlation between these two facts? If the posterior end is 

 responsible for this direction, then removal of this ought to result 

 in a different direction of gliding. The cut was made as in 

 fig. 7 and the movements of piece A watched. This piece is now 

 straight and with the posterior end removed shows no bending 

 of the body towards the left. This piece did not turn towards 

 the left but took a straight course. Again how will the posterior 

 piece behave when the anterior part is gone? Piece B, fig. 8, 

 moved forward, always swerving to the left just as the normal 

 individuals do. This shows that the direction of gliding is de- 

 pendent on the form of the animal and particularly on that of the 

 posterior tip. If the movements of the anterior piece (piece A, 

 fig. 8) are watched, it will be noticed to be moving in circles to 

 the right and duplicating the conditions on the surface film. By 

 reason of the cut only the anterior end of the animal reacts on 



