INCOMPLETE REGEN'ERATION IN LEPTOPLANA LITTORALIS 189 



So far then the results showed nothing different from what had 

 already been observed in other forms, but the power to regener- 

 ate ganglia had been tested only in pieces from which the tissue 

 anterior to the level of the ganglia had been cut away, and the 

 question remained whether that power was entirely wanting under 

 all conditions. The ganglia were accordingly removed in a num- 

 ber of ways, ail differing from a cut straight across the worm in 

 that some of the tissue anterior to the level of the ^anp'lia in each 



o o 



case remained in the piece that was to regenerate. The worms 

 were cut as follows : 



1. The ganglia were removed with as much of the tissue an- 

 terior to them as was necessary to make the cut, leaving how- 

 ever parts of the anterior end of the worm on both sides of the 

 cut (Fig. A, i). 



2. The ganglia were removed from the side, with as little as 

 possible of the lateral tissue and leaving all of the anterior tissue 

 (Fig. A, 2). 



3. The ganglia were removed in a right-angled piece, leaving 

 the lateral part of the anterior end on one side (Fig. A, 3). 



4. The ganglia were cut out with a straw, leaving a round hole 

 in the worm (Fig. A, 4). 



5a. The worm was cut in half longitudinally, and the ganglia 

 removed from the pieces, or the ganglia were first removed with 

 a straw, and the worm then cut (Fig. A, 53). 5b. A slight varia- 

 tion of 5a was made by removing the ganglia with a straw, and 

 a few days later, when the wound had closed, cutting the worm 

 longitudinally (Fig. A, 5b). 5c. The anterior half of one side 

 was cut off, and the ganglion of the other side cut out (Fig. 

 A, 5 c). 



In all of these cases, unless as in a few instances the wound 

 healed in such a way as to prevent growth of new tissue, regen- 

 eration took place, and externally, the worm appeared to be 

 rapidly attaining the normal condition. The worms were not 

 always kept until the form was completly restored, but regenera- 

 tion in Leptoplana : Anterior and Lateral Regeneration," Jour, of Exp. Zoo!., Vol. 

 I., p. 513, 1904. Among other results, he has found that anterior regeneration is 

 complete when not much more than half of the cephalic ganglion is removed by a 

 cross-cut. 



