POLARITY OF PRIMARY OOCYTE. 



221 



In studying total preparations of the ovarian eggs one soon finds that 

 the projected portion of the follicles is more conspicuous than the discharged 

 eggs, and so much so that one can hardly deny that it represents the 

 portion that was attached to the ovarian wall (Figs. 3 and 4). Sections 

 through the ovary has confirmed this surmise. As shown in Figs. 1 

 and 2, the follicular membrane, with nuclei here and there, is produced 

 over the pointed end of the egg ; unquestionably it is the attachment 

 surface to the ovarian wall {cf. LUDWIG and HAMANN. Taf. VI, Fig. 2.) 



From what has been described it may be concluded that in the 

 egg of Asterias forbesii the point of attachment of the primary oocyte 

 coincides neither to the animal pole as in Strongylocentrotîis, nor to 

 the vegital pole as in Cerebratiilus. In this case, the longitudinal axis 

 of the germ-epithelial cell, therefore, docs not correspond to either 

 the egg-axis or the embryonal axis. This conclusion has been reached 

 from examination of the pyriform eggs, but may safely be extended 

 to all the eggs. 



Zoological Institute, 



Imperial University, Tokyo, 

 Sept, 27, 1910. 



Literature. 



Garboyvski, T., '04. — Uber parthenogenctische Entwickelung der 

 Ästenden : Bull, de l'académie des sciences de Cracovie, No 

 10. Art. 56. 



HARTMANN. M., '02. — Studien an tierischen Ei. I. Ovarialci und 

 Eireifung von Astcrias glacialis : Zool. Jahrb. 15. 



Jordan, II. E., '08. — The relation of the nucleolus to the chro- 

 mosomes in the primary oocyte of Astcrias forbesii: Carnegie 

 Institution Publication 102. 



Ludwig, H. and Hamann O., '99. — Bronx's Klassen und Ord. 

 des Tierreichs. 2. 



Wilson, E. B. and Mathews A. T., '95. — Maturation, fertiliza- 

 tion, and polarity in the echinoderm egg: Journ. Morph. 10. 



