MORGAN. 



[VOL. II. 



In another experiment grafted April 28 (2.30 P.M.), as shown 

 in Fig. 2, and cut off April 29 (10 A.M.), two individuals formed 

 abnormal tails and a third a compound tail. The tail of this 

 individual is represented in Fig. 6. On the ventral side of the 

 new tail are found the slate-colored cells of the major compo- 

 nent, and on the dorsal side the yellow cells of the grafted 

 piece. (It is not possible to show this difference satisfactorily 

 in a simple uncolorecl drawing, since the principal difference is 

 one of color.) In addition to this difference one can see in the 

 region at which the grafting took place and where the new 

 tissue arises from the old that each component contributes its 

 half to the new tail. Moreover, in all these cases the tadpoles 



had been carefully ob- 

 served from day to day 

 (and not only at the 

 intervals recorded in the 

 text) and the gradual 

 formation of the com- 

 pound tail observed. 



In another experiment 

 on April 28 the tail was 

 cutoff on April 29. One 

 of the tadpoles did not 

 regenerate a new tail, 

 another (R. sylvatica) had a compound tail, and one had a bifid 

 tail, one branch being compound. Finally in another series in 

 which nine grafts were made, one produced a compound tail, 

 another may have contained a small amount of the major 

 component in the new tail, six regenerated entirely like the 

 minor component, and one was abnormal. 



In addition to these cases there were three others (in the 

 total of sixty cases) in which there was an overlapping of the 

 two components in the tail, as in Fig. 6. In two of these 

 the core of the new tail came from the minor component, but 

 it is highly probable that a small addition came from the major 

 component also. In the third case the new tail contained at its 

 more distal end elements from both components. Unfortunately 

 this lot was killed accidentally before they regenerated further. 



FIG. 6. 



