PHYSIOLOGY OF REGENERATION IN TUBULARIA. I 5 I 



24 hours 10 of 55 pieces showed only oral primordia. Twelve 

 hours later 29 of 55 pieces had oral primordia, and of these 3 

 pieces were double — two of them having the basal end ahead. 

 Three other cases are summarized in the table. 



48-50 Hours. 



Oral. Double. Easal. Nothing. 



10 3 4 



19 14 5 



9 27 4 



These facts show that despite the " rule," the number of double 

 and basal polyps is considerable. Pieces similar to these must be 

 present when the oral ends of pieces are tied. Consequently the 

 rate of basal development of many of the tied pieces may have 

 no connection with the tying of the oral end. Nevertheless 

 comparisons with the control show unmistakably that the per- 

 centage of basal polyps is greatly increased by oral ligatures. 



In order to see whether the development of the basal polyps in 

 double pieces is accelerated when the basal and the oral ends 

 develop simultaneously, pieces of moderate length were cut off 

 from the distal end of stems and the basal continuations of these 

 pieces were also kept and a record made of the time of their oral 

 development. 



In one case after 26^2 hours there were faint indications of 

 oral primordia on 15 of 34 of the distal pieces. At this time 5 

 of the basal pieces also showed oral primordia. Seven hours 

 later the former pieces had 2 1 oral, the latter 6 oral primordia. 

 Fifteen hours later the former had 29 oral, the latter 1 5 oral 

 primordia or polyps and one double primordium. The same pro- 

 portions were found 48 hours later. In this case no double pieces 

 developed at first among the distal pieces, although the proximal 

 pieces early showed primordia. This negative result shows that 

 the basal development of double pieces is not necessarily corre- 

 lated with the oral development of their basal partners. 



In another case, of 50 distal pieces, after 26 j4, hours, 14 had 

 oral primordia, the 25 basal pieces had 10 oral primordia. Seven 

 hours later the former had 25, the latter 18 oral primordia. 

 Twenty-seven hours later still the former had 32 oral primordia 

 and one basal primordium, the latter 23 oral and one double. 

 Later the same relations held. 



