230 



C. W. Halm. 



diglyphic polyps mentioned in the fifth column of Table II. 

 This peculiar monoglyphic polyp may be considered the result 



Table II. 



Character of polyps produced by basal fragments cut from monoglyphic and from diglyphic 

 parents respectively, the relation of the cut to the parental directives being unknown in a majority 

 of cases. M = monoglyphic; D = diglyphic. 



of the union of the cut edges of the parental fragment without 

 regeneration of a directive system. Such a result occurs not 

 infrequently in the case of fragments containing only non-direc- 

 tive mesenteries, as well as of those, like this one, which contain 

 a pair of directives. In the former case wholly aglyphic polyps 

 are produced. Three such were observed in these experiments. 

 Carlgren ('04) has shown, in the case of Sagartia, that such a 

 result is obtained most often when the parental fragments are 

 of relatively large size. It is probable that the same is true in 

 Metridium, though precise observations on this point are wanting. 

 The monoglyphic polyps of diglyphic parentage, like those of 

 monoglyphic parentage, had the directive mesenteries in all cases 

 except one (out of a total of twenty-five) in the regenerated area. 

 In that one case the single pair of directives was clearly received 

 directly from the parent polyp and no new directives had been 

 regenerated. Likewise in the case of the diglyphic polyps no 

 difference was recognizable between those of monoglyphic 

 parentage and those of diglyphic parentage. In all cases except 

 possibly one there was a pair of directives in the old tissue, and 

 one in the new. There were three diglyphic polyps of this sort 



