Nachdruck verboten, 

 tlbersetzungsrecht vorbehalten. 



Inequality of the two Eyes in regenerating Planarians. 



By 

 H. W. Kaud and E. A. Boyden. 



(Contributions from the Zoological Laboratory of the Museum of 

 Comparative Zoology at Harvard College, No. 243.) 



With 10 Fignres in the text. 



' The observations described in this paper ^) resulted from an 

 attempt to repeat, for a special purpose, such experiments as have 

 been described by Voigt (1899).^) The experiments referred to 

 consisted in making oblique incisions into the side of the body of a 

 planarian without removing any part of the animal. The cut edges 

 were prevented from permanently growing together by frequently 

 reopening the wound. Projecting lateral slips of tissue are thus 

 produced. They develop new tissue along the healed cut edge. If 

 the slip be one whose base represents a more posterior portion and 

 the free tip a more anterior portion of the original tissue, a new 

 head may develop in the anterior region of the new tissue on the 

 mesial side of the slip, and in some cases a tail appears in the new 

 tissue which develops along the corresponding cut edge of the main 

 portion of the worm. It is not clear whether this new tail is corre- 



1) The experimental work upon which the paper is based was carried 

 out by E. A. Boyden. The senior author is mainly responsible for this 

 account of the work. 



2) See also Lemon (1900). 



