132 



REGENERATION 



that part of the edge that is nearer the base of the tail (Fig. 40, C\ 

 This growth continues to go on faster on the lower side, until the 

 rounded form of the tail is produced. If we make the oblique cut so 

 that the part nearer the base of the tail is on the upper side, the result 

 is the same in principle ; the upper part of the new material grows 

 faster than any other part. If we make two oblique cuts on the same 



B 



H I 



FlG. 40. A. Tail of Fundulus heteroclitus. Lines indicate levels at which B and Cwere cut off. 

 B. Regenerating from cross-cut. C. Regenerating from oblique cut. D, E. Regenerating 

 from two oblique surfaces. G. Tail of stenopus. //, /. Tail of last cut off squarely and 

 obliquely. 



tail, as shown in Fig. 40, D, or as in E, the new part grows 

 faster in each case on that part of the cut-edge that lies nearer the 

 base of the tail. These results may be supposed to be due to the better 

 nourishment of the new tissues nearer the base of the tail ; but it is 

 not difficult to show that the difference in the rate of growth over 

 different parts of the cut-edge is not due to this factor. If, for 



