Dunorphistn and Regeneraiioti iti Mctridiuni. 227 



supposedly produced by fission in nature. The greatest success, 

 however, was attained when fragments were cut from the basal 

 portion of a polyp, as in the natural process of basal fragmen- 

 tation. In either case the number of siphonoglyphs in the parent 

 polyp was determined, so that the fragments from monoglyphic 

 and diglyphic parents might be kept separate. 



Diglyphic and monoglyphic parent polyps could be distinguished 

 either by inspection externally, when they were fully expanded, 

 or by cutting the contracted polyp across after removing frag- 

 ments from its base. The fully regenerated young were stupefied 

 by means of magnesium sulphate and fixed in chromic acid 

 (i per cent) then imbedded in paraffin and sectioned. Staining 

 the sections with haematoxylin and eosin made it possible, with 

 a low power of the microscope, to decide the various questions 

 on which the interpretation of a polyp's structure depends. 



Fragments cut from monoglyphic polyps produced twenty- 

 eight monoglyphic and five diglyphic individuals. (See Table II.) 

 Three of the diglyphic polyps were simple, i. e., having a single 

 oesophagus to which the two pairs of directive mesenteries were 

 attached; two were double, i. e., having a divided oesophagus, 

 each branch of which was connected with a different pair of direc- 

 tive mesenteries, as if a portion of oesophagus had been produced 

 in connection with each pair of directives, but the two portions 

 had failed to unite. 



There were also twelve polyps regenerated from fragments cut 

 from monoglyphic parents, which up to the time when they were 

 examined had developed no mesenteries which could be recognized 

 as directives. It is probable, however, for reasons which will 

 presently appear, that most, if not all, of these would have become 

 unmistakably monoglyphic polyps had they been given a longer 

 time for regeneration. 



Fragments cut from diglyphic polyps produced in all thirty- 

 six monoglyphic and ten diglyphic polyps, all simple, as well as 

 two polyps whose character was indeterminable. 



These experiments show conclusively that each sort of polyp 

 can produce the other by asexual methods; but, it will be observed, 

 the diglyphic parents produced a somewhat greater proportion 

 of diglyphic young, and the question at once arose whether this 

 might not be due to an hereditary influence. A more careful 

 study, however, of the regenerated polyps showed that such was 



