1 68 T. H. MORGAN. 



was no evidence that it would have done so if the fish had been 

 kept longer. Since the operation had been carried out during the 

 height of the breeding season, it seemed possible that the spot 

 might normally fade out later, but other fish, examined in Sep- 

 tember, showed the spot still present. 



The results on Fundnlns appear to be different from those on 

 the gold fish, and it is not apparent why this difference should 

 exist. The result does not seem to be connected in any way 

 with the fact that the spot in Fuudulus is a secondary sexual 

 organ. The most plausible explanation that suggests itself is 

 that in the tail of a gold fish that has a black tip there are cells 

 throughout the tail that can develop pigment should they get 

 into the terminal portions of the tail, while no such cells are pres- 

 ent in Fnndnlns, or if present they fail to produce pigment in the 

 new part. It may be that in Fundnlns all the cells capable of 

 producing pigment have been already carried into the pigment- 

 spot itself, and hence when this spot is removed no cells capable 

 of developing this pigment are present in the remaining part. 

 Further work will be necessary to determine whether these sug- 

 gestions have any value. 



THE METHOD OF CLOSURE OF THE CUT ENDS OF TUBULARIA. 

 The peculiar method of closure of the cut ends of Tnbnlaria 

 has attracted attention since it appears to be different from the 

 closing observed in other forms. I have already discussed at 

 some length this process 2 and shall not repeat here what has 

 been already said, but since I have observed during the past sum- 

 mer certain processes that seem to throw some light on this ques- 

 tion I shall briefly refer to them in this connection. Stevens has 

 figured the closed end of a piece that had been cut through the 

 hydranth-forming region at the time when the primoidium of the 

 new hydranth had just been laid down, and when the red pig- 

 ment lines, that indicate the appearance of the new hydranth, 

 were present. Over the closed end the red lines radiate to the 

 center of the bounding membrane. It seemed to me that a 

 further examination of pieces that closed in this way might throw 

 some light on the process in general. Pieces were cut off and 



1 Morgan, Ronx 1 s Archiv, XIV., 1902. 

 2 " Regeneration," 1901, p. 69. 



