ASEXUAL REPRODUCTION IN SAGARTIA 169 



esophagus apparently remains (p. 171 ff.)- Absorption of old 

 mesenteries, so constant a feature of asexual reproduction in 

 some other species, does not occur here (p. 171, 172, 200), except 

 probably in the case of mesenteries torn during division. So 

 far as I can judge, the rate of formation of new cycles of incom- 

 plete mesenteries is not altered. No new orange stripes are 

 formed in the old region as a result of division. A general fading 

 of the brighter colors occurs in all specimens kept under the 

 artificial conditions of the laboratory, but this is not noticeably 

 greater in regenerating polyps than in apparently undivided 

 ones. It appears, then, that the form of the older part is not 

 changed in consequence of fission and that the formation of new 

 structures is strictly confined to the region of union of the torn 

 edges, where a broad sector of new material is laid down. The 

 rate at which regeneration goes on is strikingly variable. In 

 the following account the estimated periods must therefore be 

 regarded as rough approximations, from which individual 

 specimens may be expected to diverge widely. 



PLANE OF FISSION 



In fission of the type described above, there are many planes 

 in which the tear may pass through the column of the anemone. 

 It is my purpose in this section to discover any tendencies of the 

 plane of fission to occupy spaces of one kind rather than another. 

 Part of the material upon which is based my study of such tenden- 

 cies consists of specimens observed in process of division and sub- 

 sequently isolated and allowed to regenerate for different periods 

 before being killed. The mesenteric formulas of these animals 

 of known relationships are given in tables 3, 4, and 5.^ Table 6 

 presents the formulas of additional specimens available for this 

 study. Before directing attention to the tendencies indicated by 

 these tables it is desirable to make clear the standing of the 

 additional specimens included in table 6. Study of specimens 



2 For interpreting the tables and figures, to which frequent reference is made 

 in the text, an acquaintance with the symbols and general explanation given 

 on pages 232 and 233 is essential. 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 28, NO. 2 



