92 BULLETIN : MUSEUM OF COMPAKATIVE ZOOLOGY. 



later stages in Asplauchna, and demonstrate clearly that it lies at the 

 animal pole of the egg, opposite the blastopore. 



^Moreover, a careful examination of Zelinka's own work shows that 

 tlie general statement above cited cannot be considered correct for all 

 Eotifera. His general conclusions are based throughout primarily' upon 

 his more complete study of Callidina, and in his " Theoretischer Theil " 

 he seems to have overlooked the fact that in Melicerta the place of 

 polar-cell formation observed by himself was, not only not near the 

 anterior end, as noted in the above general statement, but also not upon 

 the dorsal side. 



Tiie egg of Melicerta is described (Zelinka, '91, p. 11.5) as an elon- 

 gated ovoid with a sharper and a thicker or blunter end ; one side is 

 cylindrical in form, so as to appear straight in profile, while the other is 

 swollen, presenting in profile a convex outline. Zelinka says in regard 

 to the orientation of the egg given by Joliet : "Da ganz richtigerweise 

 das dickere End als das Kopfende, das diinnere als das Hinterende 

 bezeichuet wird, sowie ferner dieser Autor dessgleichen richtig die vorge- 

 bauchte Fliiche als die ventrale, die cylindrische als die dorsale ansieht, 

 so ware die Orientu'ung durch diese Form des Eies eigentlich erleich- 

 tert," etc. Xow, in Zelinka's figures of the maturation stages of 

 Melicerta (Taf V. Figg. 74— 7G) the polar cell is clearly shown to be 

 formed at this convex, and therefore ventral side. Furthermore, his 

 description of the process of maturation is as follows : " Das Keimblas- 

 chen zeigt zuerst noch seine wohlbegreuzte spharische Gestalt (Fig. 73) 

 uud liegt etwa in der !Mitte des Eies, sodann wandert es, indem es leb- 

 haft seine Gestalt verandert, gegen den hinteren Pol, wird zu einem 

 halbniondformigen Fleck mit gekerbten l^iindern (Fig. 7-t), dessen Ivon- 

 vexitat der Bauchjlache zugekehrt, welcher es sick rasch ndhert. Knapp 

 unter der Oberfliiche zerlegen die Kerben den Kern in drei eng an 

 einander liegende ungleiche rundliche Stlicke (Fig. 75), deren der Ober- 

 flache zunachst liegendes aus dem Ei gepresst wird." ^ (pp. 116, 117.) 

 The figures show clearly the convexity of the curved nucleus directed 

 toward the convex ventral surface of the egg, the gradual approximation 

 of the nucleus to that surface, and the formation there of the polar cell, 

 as described in the above passage. In the '' Erklarung der Abbildnngen," 

 these figures (73-77) are said to be " Rechte Seitenansichten," which 

 would make the convex surface and the place of polar-cell formation 

 dorsal, as required by Zelinka's general statement. But this contradicts 

 the description just quoted, and there is other proof that the orientation 



1 The Italics are mine. 



