PLATE 2 



EXPLAXATION OF FIGURES 



6 Microphotograph of a section of a specimen (no. llj, table 3) killed twenty 

 days after division. The newest area lies between the two old bounding mesen- 

 teries, (II) and c, and contains six small mesenteries- — c is complete orally. 

 The greater part of the section is occupied by an older regenerating area, from 

 (I) to (I) exclusive. Mesenteries labelled c- and c' and the mesenteries in corre- 

 sponding positions on the opposite side of the directive plane of this area are 

 complete orally. X 27. 



7 Photograph at higher magnification of the newest area and its bounding 

 mesenteries from the same section as shown in the preceding figure. X oG. 



8 A regenerating area (from no. 3a, table 3) slightly more advanced than 

 the newest part shown in figure 7, though actually younger (ten days). Bounding 

 mesenteries, (I), both incomplete. In all, twelve new m.esenteries can be counted 

 in the sections of this specimen. X 60. 



9 Far oral section of a specimen described when living as having three orange 

 stripes and one white bar in the old region, and one white bar in a regenerating 

 area which occupied approximately one-fifth of the circumference of the speci- 

 men. See diagram, figure 36. Typical regeneration following division in two 

 complete endocoels. The characteristic size relation existing among the re- 

 generating mesenteries is well represented. On each side a new mesentery, c', 

 mates with the old bounding mesentery, c. The appearance of a siphonoglyph 

 in section is shown at S in the new region and in the groove on the opposite side 

 of the esophagus. In the latter the cilia, though distinguishable in the photo- 

 graph, are not reproduced in the figure. In the upper part of the figure a fold 

 of the oral disc appears. X 40. 



10 Part of a more aboral section of the same specimen as shown in figure 9. 

 The order of size of the new mesenteries is maintained. X 40. 



11 Part of a section of an anem.one (no. 8b, table 3) killed fifty-six days 

 after division. On one side of the new directive plane only two potentially 

 complete non-directives (c^ c-) form.ed where more commonly four are re- 

 generated. Attention should be called to the probability that the mesentery c- 

 in such a region of reduced number of new mesenteries corresponds with the one 

 designated r^ of a regioii regenerating the typical number of mesenteries (p. 191, 

 197). X 34. 



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