DIFFERENTIAL INHIBITION IN OBELIA 495 



Runnstrom, J. (1917). — ^" Analytischc 8tudien iiber die Seeigelentwick- 



lung ", • Arch. Entw.-Mech.', 47, p. 22.3. 

 Schultz (1906).— Ibid., 21 (Hydra). 



(1907).— Ibid., 24 (Clavellina). 



Thacher, H. F. (1903).— " Absorption of the Hydranth in Hydroid 



Polyps ", ' Biol. Bull.', 5. 

 Vandel (1921 ).— ' Comptes-rendus Ac. Sci.', 173, p. 1014 (Polycelis). 



