154 T - H - MORGAN. 



order to see if the amount of materials set free by the breaking 

 down of the ridges near the oral end (preparatory to the develop- 

 ment there of a polyp) has an influence on the rate of basal 

 development. As a control some pieces were also tied at once 

 at the same level. One such experiment is shown in the next 

 table. 



After 48 Hours. 



Another experiment gave similar results. In a third experi- 

 ment pieces, tied near the oral end after 9 hours, produced basal 

 primordia before those tied at once. 



In this third experiment there was perhaps some indication 

 that when pieces were left open for a time at both ends and were 

 then tied at the oral end the basal polyps developed sooner than 

 when the oral ends were tied at once. This result I had 

 obtained before. The three following experiments do not give 

 the same result. 



Of 12 pieces tied at once at the oral end, 2 had basal primor- 

 dia after 48 hours. Of 1 1 pieces tied after 26^ hours 3 had 

 basal primordia. After another 24 hours the former had 5 

 primordia and 6 polyps, the latter 10 basal primordia (and one 

 nothing). These were less advanced than those tied at once. 



In another experiment 16' pieces were tied at once near the 

 oral end and produced after 48 hours 14 basal primordia. Of 

 8 pieces tied after 26 hours 6 had basal primordia. The evidence 

 seems to show that no retardation occurs (or very little) if the oral 

 ends are tied after 9—24 hours as compared with pieces tied at 

 once, and there may be an actual, i. e., an absolute acceleration. 



The results of another experiment are also still doubtful after 

 repetition of it. Pieces were left open for several hours and a 

 ligature was then tied near the oral end in some of the pieces, 

 and in others near the basal end. The time of development of 

 the basal primordia was noted in each case. Previous experi- 

 ments had given some indication that the longer basal pieces pro- 

 duced primordia before the shorter ones. It seemed not improb- 

 able, if this were really true, that the amount of material set free 



