264 c - M - CHILD. 



the tentacles are only a few millimeters in length, although this 

 piece is two months older than Fig. 4. A piece regenerating 

 in the typical manner during more than two months should 

 possess marginal tentacles 25-40 mm. in length. 



Loeb's figures and text indicate that little attention was paid to 

 the internal anatomy of the form. He states that in these rectan- 

 gular pieces the number of tentacles regenerated was a fraction 

 of the whole number possessed by the original animal correspond- 

 ing to the fraction of the total circumference represented by the 

 oral end of the rectangular piece, but no reference is made to the 

 correspondence of the tentacles with the intermesenterial chambers. 

 According to Loeb's statements and figures the tentacles appear 

 to arise from the oral cut surface of the piece in each case, but 

 according to my own observations they never arise in this 

 manner. It is difficult to understand how hollow, tubular tenta- 

 cles could arise directly from the cut edge of the body-wall. This 

 point is of some importance, since if Loeb is correct the influence 

 of internal pressure upon the regeneration of the tentacles becomes 

 at least extremely doubtful. 



In the first paper of this series ('c>3<?) the typical course of 

 regeneration in C. solitarins was described. It was shown there 

 that the new tentacles do not arise at the cut surface but at some 

 little distance from it. The margin of the body-wall rolls inward 

 after section and the tentacles arise at the highest, most oral part 

 of the rounded margin thus formed ('03*?, Figs. 13-19). 



In the specimens of C. mcinbranacens which I have observed 

 the tentacles arise in exactly the same manner. The margin 

 rolls inward and soon changes in the body-wall appear in a region 

 several millimeters distant from the actual cut surface, viz., at 

 the most oral region of the inrolled part. Thus an area extend- 

 ing about the whole circumference is established in which first loss 

 of pigment and reduction in thickness of the body-wall occur, and 

 then the new marginal tentacles appear as minute buds. 



In the open pieces corresponding to Loeb's Figs. 4-6 the ten- 

 tacles arise in exactly the same manner, though much more 

 slowly than in closed pieces. The margin of the piece rolls inward 

 and the new tentacles appear on a part of the body-wall which 

 was originally somewhat aboral to the cut surface. 



