Vol. 3] 



Bovard. — Condylostoma patens. 



365 



In an individual which was cnt into equal parts, the anterior 

 end backed up but little, but prolonged the spinning about to 

 the right before proceeding forward. In all cases where the pos- 

 terior end was removed the anterior portion showed no tendency 

 either at its posterior end or elsewhere to bend toward the left. 

 Kelatively more time was consumed in the turning part of the 

 reaction by these anterior fragments than by normal individuals. 

 The duration of the backward movement is correspondingly 

 shortened in the former. 



19 



Pig. 18. — Piece A exhibited no bending of the body during the motor re 



action. 

 Pig. 19. — Piece A executing the turning part of the motor reaction. 



There is another factor here that must not be overlooked. 

 In removing the posterior end we are losing the influence of its 

 cilia. As the pieces of the anterior end are made smaller and 

 smaller, we find that the backward movement becomes less and 

 less extensive till, when it assumes the size indicated in fig. 20 A, 

 a reversal of the cilia accomplishes nothing, and the piece reacts 

 by simply turning to the right. The number of cilia are not 

 sufficient to produce any pronounced movement while the in- 

 creased activity of the membranellae is felt immediately and 

 turns the animal to the right. Referring again to fig. 20, piece 

 B gives the normal motor reaction, the posterior tip bending to- 

 v.'ards the left during the backward movement and the cilia giving 

 their normal movements. The bending of the posterior tip ac- 

 counts for the movement of the anterior end to the riuht. 



