56 



MEMOIRS OF THE NEW YORK ACADEMY OF SCIENCES 



and the pike (later also of the trout). 1 KUPFFER says that he confirmed these obser 

 vations by sections, though none are figured. Curiously enough KUPFFER'S state- 

 ments on this subject have been discredited by the majority of later investigators, 

 though they have been confirmed by a few. Professor DOHRN informs me that he 

 years ago noted the open connection in the case of the perch but had never pub- 



FlQUEE 14. 



FIGURE 15. 



EC 



Contiguous sections of Murxna t embryo cut as above somewhat later than preceding (camera lucida drawings). 

 Pr, " prostoma " ; Yp, yolk-plug ; Kv, Kupffer's Vesicle ; GBy, gut-hypoblast ; NeHy, " non-embryonic " hypoblast ; 

 EC, cells embedded in periblast. 



lished this observation. HENNEGUY ('88) noticed this condition in the case of the 

 same fish but later concluded that he had been in error. He did not deny, how- 

 ever, the possible accuracy of Kupffer's observation. RAFFAELLE ('88) observed in 

 the living egg of Uranoscopus and in an unknown pelagic egg that KupfFer's Vesicle 

 was for a brief period connected with the exterior through the blastopore. This 

 connecting passage he regarded as equivalent to the neuren- 

 teric canal. MC!NTOSH and PRINCE ('90) also speak of "what 

 seems to be a tubular connection of the external blastopore and 

 I pr the ventral surface of the embryo" but cannot be sure of an 

 open passage into Kupffer's Vesicle. As none of these authors 

 sectioned the eggs, we do not know whether the canals described 

 had cellular walls or merely lay in the periblast. The "linear 

 Optical section of egg of canal" mentioned by AGASSIZ and WHITMAN ('84) was evi- 

 dently meYel y the disa PPearing blastopore. 



There is then every reason to believe that the open invagina- 

 tion occurring in Murse.no, f and probably certain other fishes is represented by the 

 ingrowing cell-mass found by Kowalewski in Carassius and Gobius and by myself in 

 Amiurus, Noturus, Salvelinus, Fundulus and Ctenolabrus. The presumption is that the 

 solid condition is the more frequent among the teleosts. This masked form of invagina- 



'The vesicle was first described by KUPFFER in 1866 in the embryos of Gasterosteus and Goliius. Its origin by in- 

 vagination was not at that time maintained. SOBOTTA ('98) states that COSTE had figured the vesicle in 1847. LERE- 

 BOULLET also ('63, figure 22) represents what appears to be Knpffer's Vesicle. 



