152 



T. H. MORGAN. 



In a third case, after 24 hours, 6 of the distal pieces had oral 

 primordia, and none of the basal pieces had developed. Twenty- 

 four hours later the former had 32 oral primordia and one basal. 

 Some of the basal pieces had developed. Twenty-four hours 

 later still the former had 33 oral, 3 double and one basal pri- 

 mordium ; the latter 8 oral. 



In a fourth case, after 48 hours, the distal pieces had 16 oral 

 and two double premordia ; the basal pieces showed 1 1 oral, 4 

 double and 6 nothing. 



In a fifth case, after 48 hours, the distal pieces had 28 oral and 

 13 double primordia; the basal pieces 12 oral and one double 

 primordium. 



The results seem to show no acceleration owing to oral de- 

 velopment, and on the other hand no necessary retardation if 

 both primordia start at the same time. Local factors must there- 

 fore determine the results. Most of the distal pieces served also 

 as controls in cases in which the oral ends of other pieces had 

 been tied. In. all such cases there was a very great excess of 

 basal primordia in the orally -tied pieces, showing that there is a 

 distinct effect produced in this way. It would seem therefore 

 that despite the fact that both oral and basal polyps may develop 

 simultaneously, the oral development, if it gets the start, inhibits 

 to some extent the beginning of basal development. The nature 

 of this influence is still obscure. 



Are the Changes in Isolated Pieces Local or General ? 

 Pieces were tied near the oral end and then after a number of 

 hours as much of the basal end as would contain the primordium 

 of the polyp was cut off. In the first experiment the basal cut 

 was made ten hours after tying. Twenty-three hours after the 

 beginning 3 of 9 pieces showed basal primordia. In the control 

 (tied but not cut) 3 of 9 pieces also showed basal primordia. 

 The removal of the basal piece had not, within a total of twenty- 

 three hours, delayed the basal development. In other words the 

 cut end did in thirteen hours what it took the control twenty-three 

 hours to do. This means that the rate of regeneration was acceler- 

 ated by changes taking place in the pieces at least some little dis- 

 tance from the cut end. No doubt the development would have 



