EMBRYOLOGY OF CLEPSINE. 231 



tion of such eggs in a living condition. If a worin^ about to 

 deposit, be cut transversely through the middle, the eggs thus 

 liberated will, in some cases, show a white spot on one pole. 

 This spi)t, examined more closely, shows a distinct radial struc- 

 ture (fig, 1). Sections of such eggs prove that this polar 

 figure marks the place of the external pole of the amphiaster. 

 Sections of those eggs in which the polar figure is not yet 

 visible show the amphiaster lying somewhat deeper in the yolk 

 than is represented in fig 62. 



This polar figure is visible on most eggs examined imme- 

 diately after extrusion, and alter a few minutes on all. I have, 

 at least twice, seen both poles of the amphiaster on fresh-laid 

 eggs of C. complanata ; but usually the inner pole lies too deep 

 to be seen from the surface. This figure was seen by Grube 

 (V " Polfleck,"' Kreidweisserpuukt^'), by Leuckart and Eathke 

 i'ww} '• weisse Scheibe"), and by Eobin ("zone foncee/' '3V), 

 and is perhaps the same as the " clear spot " seen before the 

 polar globules appear on the egg of Lamellibranchs (t/W) and 

 other Mollusca, and on the egg of Euaxes (^ |) . May not the 

 " Faltejistern '' (Geryonia, ttV-t ) be refernd to the same 

 category ? 



Qidescent State. — I once disturbed a worm as she was laying 

 the last eggs, and in consequence of the interruption three eggs 

 were retained in the ovary. 



The eggs that were laid were examined, and the polar figure 

 was found as usual. The worm manifested no desire afterwards 

 to part with the remaimng three eggs. At the end of 48 hours 

 I resorted to the method of cutting before mentioned, to get the 

 eggs. To my surprise, I found them in the same condition in 

 which I had found the others two days before. The eggs in 

 both cases were kept, and they developed in the normal manner. 

 Here was clear evidence that eggs, after the formation of the 

 archiamphiaster, remain in a comparatively quiescent condition 

 until, at the time of extrusion, they are brought into contact 

 with the water; and that this quiescent period could be main- 

 tained at least two days without injury to the egg. I have often 

 observed cases where the eggs were retained in the ovary four or 

 five days after the time when they were fully ripe for deposit. I 

 am the more certain, as, during the second summer of my 

 investigations, I was always able to fix that period with 

 sufficient accuracy to exclude failure, in every case where I made 

 the experiment of cutting the worm to obtain eggs. In some 

 cases, where the worm has not had sufficient food, or has been 

 too often disturbed, the eggs are never laid, but retained in the 

 ovary, where they gradually dissolve, and finally disappear. 

 Grube (4-^) observed one such case and inferred, erroneously as 



VuL. Will. NKW shll. Q 



