^.12 ^- J- Hohiies 



ally meet, the point of union being carried by the greater exten- 

 sion of the oral side so that it finally comes to lie on the aboral side 

 some distance behind the anterior end. 



The method of regeneration here followed in restoring the exter- 

 nal form of the body is the simplest and most direct that can 

 readilv be imagined. The elaboration of new structures is re- 

 duced to a minimum. The part of the infusorian behaves much 

 as an entire individual, narrowing the body as it advances and 

 stretching the oral more than the aboral side; and this behavior 

 seems to help mold the part into the final form. 



In order to find out how small a part of the differentiated oral 

 margin could be stretched out to form the entire oral margin of 

 the new individual a piece was cut obliquely across the body 



Fig. 3 Regeneration of small pieces from the anterior half. 



(Fig. 2), so that the oral side of the posterior portion was consider- 

 ably shorter than the aboral. In this case the general method 

 of regeneration was much as before. Both sides curve in to close 

 the cut end, the piece elongates and becomes narrowed; the oral 

 side in the movements of the animal is extended more than the 

 aboral, and we can see that it is gradually stretched forward; and 

 finally it is puslied around the anterior end. The middle part of 

 the cut surface which is becoming more and more reduced is 

 apparentlv drawn back, but this appearance is due, I think, not 

 to its being pulled back in the center, but to the extension of the 

 two sides around it. The length of the ciliated oral side when 

 regeneration is complete is considerably greater than at first. 

 There was no extension of cilia in this case upon the cut surface. 

 The anterior limit of the oral margin was very distinct and could 



