No. 2.] THE OVARIAN EGG OF LIMULUS. 177 



As these eggs were taken from the ovary of the living 

 animal, and examined at once in the fluids of the ovary, the 

 effects of reagents cannot be considered responsible for these 

 appearances. 



An examination of the same eggs in a living condition shows 

 also the vitelline-body, or sphere, and its intimate connection 

 with this peculiar inner zone of the cytoplasm (PI. XIII, Fig. 

 16, a). PI. XIV, Fig. 21, shows a similar egg in section. The 

 sphere is seen to bear a close relation to the dividing line 

 between the two zones, on the one hand, and to the polar 

 mitosome, on the other. 



Eggs showing these zones were preserved and mounted 

 entire. The main features are excellently preserved. 



General considerations. — The division of the body of the 

 egg into an outer and an inner zone has frequently been 

 observed in other eggs. Among others by Pfluger ('63), cat ; 

 Cohn ('56), rotatorian ; O. Schultze ('87), Bambeke ('75, '83), frog ; 

 Waldeyer ('70), bird ; His ('73), fish ; Will ('86), Korschelt ('89), 

 insects ; Holl ('90), Leuckart ('53), chick ; Ludwig ('74), echino- 

 derms ; Lancaster ('75), molluscs ; K. Schulin ('81), bat and 

 human ; Henneguy ('93), fish ; Goette ('75), bombinator ; J. V. 

 Carus ('50), spiders ; Leuckart ('53), Scharff ('88), Eimer ('72), 

 Ransome ('67), fish. 



The zones in Limulus eggs present all the essential charac- 

 teristics of the figures given by the above observers, and may 

 also be seen to undergo many of the modifications that have 

 been observed in other eggs ; for example, by Pfluger. 



A so-called free space around the nucleus of ordinary cells 

 has also been described ; among others, by Leydig ('88) and 

 Brass ('83). A zone around the nucleus of sperm cells has 

 recently been observed by Auerbach ('96). 



In the case of eggs the zones are usually considered as being 

 connected with the phenomena of growth and nutrition ; but 

 the manner in which they arise is a disputed question. 



Leydig and Auerbach take different views. Leydig inter- 

 prets the inner zone as a free cavity in the cell, into which the 

 nucleus has crowded by a process of budding from the cyto- 

 plasm, to which it remains intimately connected by means of a 



