Experiments on Polarity in Tubularia. 585 



than when pieces are cut out of stems that have not previously 

 been cut, and this may be due to the changes already begun at the 

 aboral end; but on the other hand the large predominance of 

 cases of regeneration at the oral end indicates that the changes 

 at the aboral end are slight, and that the original polarity of the 

 material is still the more important factor. 



