No. 2.] THE OVARIAN EGG OF LIMULUS. 169 



lining the ovarian tubes. These contain considerable quanti- 

 ties of such secretions. 



The disintegration of cells above referred to recalls forcibly 

 the condition in milk glands, as related by Foster ('93), and 

 also the account given by Nissen ('86). 



Polarity of the egg. — -Adopting the terminology of Auerbach 

 ('96), we have also here a " Kernpol " and a " Gegenpol." 

 The archoplasm and centrosome determine the position of the 

 "Gegenpol." Apparently this is the vegetative pole, for in 

 later stages it becomes especially granular. 



At the nuclear pole a hyaline area appears usually in the 

 third stage of the egg (PI. XVI, Fig. 104). This is often irregu- 

 lar, at times crescent shaped, but not sharply defined from the 

 rest of the cytoplasm. It may partly enclose the germinal 

 vesicle, the horns of the crescent gradually merging into the 

 compact area at the vegetative pole. It often presents a 

 striking similarity to the hyaline area figured by Andrews ('91) 

 in the egg of Diopatra, and recalls the polar rings in the eggs 

 of Clepsine and of Allolobophora observed by Professor 

 Whitman ('78) and Miss Foot ('96), respectively. I do not 

 know how far it could be compared to the polar differentia- 

 tion observed by Mark ('90) in the ovarian egg of Lepidosteus, 

 which would seem more closely related to the observations of 

 Stauffacher ('93) in the ovarian eggs of Cyclas. Possibly these 

 bodies are more closely related to the " Zwischenkorper " 

 described by me in connection with the egg membrane. 



For reasons which are discussed in connection with the 

 cytoplasmic zones and yolk-nucleus, I consider this area due 

 to an infiltration of substance derived from the germinal ves- 

 icle. Its position is evidently determined by the relative 

 positions of the germinal vesicle and the sphere. It always 

 appears opposite the vegetative pole. A line might be 

 drawn through the vegetative pole, the germinal vesicle, 

 and the nuclear-pole area (PI. XVI, Fig. 104). This 

 line, however, would not always pass through the point of 

 attachment of the egg where the " Zwischenkorper" is formed. 

 (See Plates.) The above statements hold true of all stages of 

 the egg from the beginning of growth. (See PI. XIV.) 



