92 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
later stages in Asplanchna, 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 
the general statement above cited cannot be considered correct for all 
totifera. 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. 
The egg of Melicerta is described (Zelinka, '91, p. 115) 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 dünnere als das Hinterende 
bezeichnet wird, sowie ferner dieser Autor dessgleichen richtig die vorge- 
bauchte Flüche als die ventrale, die cylindrische als die dorsale ansicht, 
so würe die Orientirung durch diese Form des Kies eigentlich erleich- 
tert," etc. .Now, in Zelinka's figures of the maturation stages of 
Melicerta (Taf. V. Figg. 74-76) 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 Keimbläs- 
chen zeigt zuerst noch seine wohlbegrenzte sphärische Gestalt (Fig. 73) 
und liegt etwa in der Mitte des Kies, sodann wandert es, indem es leb- 
haft seine Gestalt verändert, gegen den hinteren Pol, wird zu einem 
halbmondförmigen Fleck mit gekerbten Rändern (Fig. 74), dessen Kon- 
vexität der Bauchflüche zugekehrt, welcher es sich rasch nähert. Knapp 
unter der Oberflche zerlegen die Kerben den Kern in drei eng an 
einander liegende ungleiche rundliche Stücke (Fig. 75), deren der Ober- 
fläche zunächst 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 “ Erklärung der Abbildungen,” 
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. 
