FISSION IN ACTINIA BERMUDENSIS VERRILL 51 



glyphs, however, maintaining their individual identity along the 

 whole length of the esophagus. No evidences of any mesentery 

 connecting the upper ends of the double tube, such as those 

 recorded by Parker ('99) and by Torrey and Mery ('04) for 

 Metridium, were found. 



A transverse section of the column (fig. 7) just below the oral 

 disc showed the following arrangement of the mesenteries. 

 There were paired directives to each of the four siphonoglyphs, 

 and the right and left halves of the animal, outside of the 

 siphonoglyphs, being the right and left halves of the original 

 parent animal, remained unchanged, each having five pairs of 

 non-directives with two or three pairs of incomplete septa be- 

 tween each pair of the complete mesenteries. Between the two 

 more widely separated siphonoglyphs were two pairs of non- 

 directives, one pair to eaeh esophagus, and between these pairs 

 and the adjacent pairs of directives were the fundaments, in one 

 case of one pair, in the other, of two pairs of mesenteries whose 

 destiny whether development into complete or incomplete mesen- 

 teries could not as yet be foretold. Between the siphonoglyphs 

 of the other end of the double oesophagus were the fundaments 

 of but one pair of mesenteries. 



A transverse section of actinia B at the level of the opening 

 of the oesophagus into the gastrovascualr cavity (fig. 8) showed 

 practically the same arrangement of the mesenteries as in figure 

 7, except that there were no signs of any intermediate septa 

 between the two pairs of directives of the sister siphonoglyphs. 



As is evident from the above description, the planes of sepa- 

 ration of the animals were parallel to the long axes of the original 

 mouths. Each siphonoglyph was halved and apparently one 

 directive of each pair also went to each daughter half, making 

 the division plane fall in entocoelic spaces in both cases. This 

 agrees with the results as shown in Metridium, where division 

 was always either entoceolic or ectocoelic, never half one and 

 half the other. 



The evidence also seems to point to the fact that, in Actinia 

 bermudensis at least, longitudinal fission does exist, and that 

 double-headed and double-mouthed specimens may be stages in 



