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N. YATSU : 



arc invariably formed half-way between the equator and the rounded 

 pole of the egg. In such eggs, therefore, the maturation axis, that 

 is, the axis through the centre of the egg and the polocytes, makes 

 a certain angle with the longitudinal axis of the egg as is seen in Figs. 

 6 and 7. As far as my observation goes, the first cleavage plane passes 

 through the maturation axis, as has been noticed by MATHEWS ('95 

 P- 338) ; the maturation axis corresponds in this species to the egg 

 axis and also to the embryonal axis. In the egg of Asterias glacialis 

 the relation seems to be quite different according to GARBOWSKI ('04 

 pp. 816 and 819). 



Fig. I. Young ovarian egg (section). Fig. 2. Nearly full grown ovarian egg (section). 

 Figs. 3. and 4. Primary oocytes just shed (total preparation). Fig. 5. Primary oocyte with a 

 fading germinal vesicle (from life). Figs. 6 and 7. Two matured eggs (from life). All the 

 figures are camera drawings x 190. 



