Grafting of Tubularia 33 1 



(C) At the time of removal of the basal piece (Figs, i and 2) 

 no sign of the tentacles' ridges was visible, and it was possible in 

 only a few cases to see circulation at the aboral end. It does not 

 follow however from this that there was no preparation for a 

 hydranth. It was difficult to keep these short pieces oriented, 

 therefore the results are meager. I have thrown out all those 

 about which there was any doubt, so that the table gives a record 

 of only twenty pieces. 



TABLE 3 c 



Hydranths at the aboral end first 8 



Hydranths at the oral end first 6 



Hydranths at the aboral and oral ends simultaneously 2 



No hydranths 4 



Total number of pieces 20 



On the eight pieces forming aboral hydranths first, the oral 

 hydranths followed very quickly, a much shorter space of time 

 intervening than between oral and aboral hydranths when the oral 

 form first. These double ended pieces were kept until the hy- 

 dranths dropped off, and a second set developed. In spite of the 

 fact that those on the aboral end developed first, the second set 

 appeared on the orals ends first, the aboral forming two days 

 later. The pieces thus returned to their original polarity. 



It is hardly possible to draw conclusions from such a small 

 number of pieces, but the results are sufficient to show that the 

 aboral hydranths after they are once developed do not exert 

 enough influence over the region from which they come to estab- 

 hsh permanently a marked polarity. 



In order that we may compare one series as a whole, I have made 

 the following table giving the relative time of formation of the 

 hydranths on the pieces A, B and C. The region of the graft is 

 indicated in J by the short horizontal fine. The numbers placed 

 beside the pieces show the order of emergence of the hydranths, 

 the letter S stands for a stolon. Where no letter or number appear 

 there was no regeneration. The arrows point toward the oral end 

 of each piece. 



