582 T. H. Morgan and N. M. Stevens. 



[c) 9 pieces 15-20 mm. long were tied 16 hours after they were 

 cut. The aboral polyps (8) appeared on an average of 83.3 

 hours, 15.5 hours later than those tied at once. 



(d) 19 pieces 15-20 mm. long were tied 24 hours after they 

 were cut, 7 in the middle, 5 about 5 mm. from the oral end of 

 the piece and 7 about 5 mm. from the aboral end. 



The average time for the aboral polyps (7) in the pieces tied 

 in the middle was 94.1 hours — -24.3 hours more than for those 

 tied at once. For those tied near the oral end (4) the average 

 was 1 01. 7 hours, and for those tied near the aboral end 102 hours 

 — 31.9 and 32.2 hours, respectively, more than for pieces tied at 

 once. 



From the results obtained in all but the last two sets of pieces, 

 it appeared evident that it is immaterial whether the pieces are 

 tied when cut, or from 8 to 24 hours later, /. e., the changes that 

 were going on at the oral end before the pieces were tied had no 

 retarding effect on the aboral hydranths. 



The discrepancy observed in the case of the pieces tied near 

 the oral and aboral ends after 24 hours, was so great that the 

 experiment was repeated twice. The results, however, were too 

 erratic to be reliable. The peculiarities were probably due to 

 individual differences in the stems used, as other conditions were 

 apparently the same. Several aboral stolons were produced in 

 both of these latter sets. 



In connection with this experiment Loeb's experiment of cut- 

 ting out pieces between the ligature and the aboral hydranth was 

 ^repeated. In one case the oral and aboral hydranths appeared 

 ^t vhe same time; two pieces, cut very near the aboral polyp, 

 developed aboral hydranths and nothing at the oral end; six 

 pieces had oral polyps and stolons or nothing at the aboral end. 

 The evidence, though not abundant, is in favor of the supposition 

 that the polarity of the whole piece is but slightly affected by the 

 development of an aboral polyp. 



Experiment 15. Several long pieces, which had regenerated 

 a hydranth at the oral end and a stolon at the aboral end, had 

 their oral ends stuck into sand without cutting off the hydranth, 

 and after 4, 5 or more days a hydranth was formed at the uncut 



