No. i.] 



REGENERATION OF TISSUE. 



I I 



Experiment I.- -The tail of R, paliistris had been grafted 

 upon the body of R. sylvatica. The tadpole appeared at the 

 time of the second operation, as shown in Fig. 2 A (April 25). 

 The dark ectoderm of the major component--^, sylvatica - 

 had grown out over the base of the tail of the smaller com- 



FlG. 2 A. 



ponent (R. paliistris}. The region of union of the inner tissue 

 can be seen where the dark and the light parts meet. The tail 

 was then cut off, as shown by the vertical line in the figure. 

 In consequence, there was left exposed at the cut end of the tail 



FIG. 2 B. 



the inner tissues derived from R. palustris, and the outer from 

 R. sylvatica. Anew tail began to regenerate, and during all of 

 its subsequent development the new tail was made up of ecto- 

 derm exactly like that of the major component, and of inner 



FIG. 3. 



tissue whose pigment cells resembled those of the minor com- 

 ponent. In other words, both inner and outer tissues regener- 

 ated their kind and showed no commingling of characters. 



Experiment II. - - In this experiment the major component 

 was R. palustris and the minor R. sylvatica. After the new 



