vol.i.] Torrey-Mery. — Regeneration in Sagartia Davisi. 223 



tins result. 8. davisi offers no difficulties in this direction; more 

 than 50 per cent of the anemones operated upon gave positive 

 results. The facts obtained up to this time are given below. 



Twenty polyps were divided by transverse cuts into oral por- 

 tions which included mouth and tentacles, and aboral portions 

 which included the foot disk. Nine were cut through the capitu- 

 lnm, so that the oral portions were very short. Eleven wen' cut 

 so that the oral portions were each half the length of the original 

 column. 



Of the nine shorter pieces, four rested with mouth disk 

 upward, five with aboral end upward; two of the former, but 

 none of the latter, had developed hyranths in five weeks. 



Of the eleven longer pieces, four rested with mouth disk 

 upward, seven with aboral end upward; in less than four weeks 

 all of the former had developed aboral hydranths, while of the 

 latter five had developed aboral hydranths, one had produced 

 both foot and hydranth aborally and one was a normal polyp. 



With respect to the factors involved in these results, Hazen 



has suggested that the position of the axis in regenerating pi s 



of S. luciae might be determined by a geotropic influence or by 

 a combination of geotropism and stereotropism; the foot disk 

 being formed at the point of contract (itself determined by 

 gravity), the hydranth at the opposite (upper) end. This sug- 

 gestion hardly fits the facts of heteromorphosis which have been 

 enumerated. Gravity cannot determine the presence or absence 

 of an aboral hydranth when the latter develops regardless of the 

 orientation of the piece. We cannot speak so surely about the 

 fact. u- of contact. It is possible that the aboral cut surfaces of 

 the pieces in our experiments which are resting mouth up, did 

 not touch the substratum for a sufficient length of time to deter- 

 mine the development of ,-, foot disk; they certainly did not 

 adhere. On the other hand, it is odd that the only foot disks 

 developing on the aboral ends of pieces, appeared on two longer 

 pices, both of which rested on their mouth disks, not on the 

 aboral cut surfaces. Internal factors seem to have been more 

 potent than externa] in this case. It is probable, however, that 

 future experiments will show a certain influence of contact upon 

 the development of the foot disk in regenerating pieces to 



