112 MORGAN. [VOL. II. 



confirm in every way those given in my former paper. In the 

 experiments made this spring my main object has been, how- 

 ever, to carry out the experiment in such a way that there 

 would be left at the exposed edge, when the grafted tail was 

 cut off, the internal tissues of two species. In this way I 

 hoped to be able to determine more definitely if, in the 

 newly regenerated part, the tissues mutually influence each 

 other. 



The day after the grafting had been performed (i.e., after eight- 

 een to twenty-four hours) the tail was cut off at the region of 

 union of the two components, as shown by the line a-a in Fig. i. 

 In this way there is left at the exposed edge not only the ecto- 

 derm of the two species, but the inner tissues also. The regen- 

 eration that takes place from the exposed edge will include 

 material derived from both components. Two possibilities 

 presented themselves. First, would the new part be formed of 



cells intermediate in 

 character between the 

 two species as the 

 result of an interaction 

 of the cells on each 

 other ; or, second, 

 would the new material 

 preserve the character- 

 istics of the region 



FIG. 2. r . , 



from which it arises, 



or, in other words, one-half of the tail show the characters 

 of one species and the other half of the other species ? It is 

 further possible that the new cells might intermingle, and if so 

 the tail might appear to be of a hybrid character. 



Other experiments of minor interest have also been studied. 

 For instance, in several cases the grafted tail was cut off after 

 twenty-four hours very near its line of union to the major 

 component, as shown in Fig. 3, A, B. The experiment was 

 made in order to see if the major component might not have 

 some influence on the regenerated part from which it is sepa- 

 rated by only a narrow band of tissue of the minor component, 

 but no such influence was observed. 



