No. 2.] THE OVARIAN EGG OF LIMULUS. 209 



EXPLANATION OF PLATE XIIL 



Fig. I. Germinal vesicle with a crescent-shaped nucleolus, containing within 

 it a reticulum resembling that of the germinal vesicle. 



Fig. 2. A female Limulus with dorsal carapace removed, showing the netted 

 ovary, the ovarian tubes on the right, ov.t., being filled with eggs. The left side 

 represents the condition in younger animals before eggs have been discharged into 

 the ovarian tubes ; ov., young growing eggs ; an., anus ; op., operculum ; g.o., 

 genital openings ; ca., carapace ; ov.t., ovarian tubes extending along the alimentary 

 canal, al.c, to the anus ; ov.d., terminal oviducts. 



Fig. 3. Germinal vesicle showing " Nebennucleoli," and a body resembling 

 these within the " Hauptnucleolus." 



Fig. 4. Germinal vesicle showing a nucleolus having numerous internal 

 bodies, one of which is about to be extruded. 



Fig. 5. An amoeboid germinal vesicle containing a large nucleolus, in which 

 there is a large vacuole containing nothing stainable. 



Fig. 6. Germinal vesicle, containing a large hollow nucleolus in the form of 

 a deeply staining shell. Within the nucleolus there is a granular network resem- 

 bling the network of the germinal vesicle. 



Fig. 7. Germinal vesicle showing diverticula, and containing a ring-shaped 

 nucleolus containing within it a network resembling that of the germinal vesicle. 



Fig. 8. Germinal vesicle with diverticula, and containing a nucleolus having 

 a radial striation, a central granular mass, in which is imbedded a deeply staining, 

 homogeneous spherical body — the endonucleolus. 



Fig. 9. Germinal vesicle ; a nucleolus in form of a deeply staining crescent 

 containing a finely granular substance surrounding a vacuolated endonucleolus. 



Fig. 10. An egg with its germinal vesicle containing a nucleolus, and also a 

 radial arrangement of the chromatin network about a center resembling a centro- 

 some. 



Fig. II. The nuclear pole (" Kernpol ") of an egg about to be discharged from 

 the follicle, showing the position of the germinal vesicle, and the spongy polar 

 protoplasm spreading out under the egg membrane. 



Fig. 12. Mature egg of the ovarian tube, showing an amoeboid remnant of 

 the germinal vesicle, and its connection with a peripheral mass of protoplasm. 



Fig. 13. Portion of an egg showing the formation of the egg membrane after 

 the first layer has been formed ; the orderly radial arrangement of the protoplas- 

 mic fibers previous to the hardening of the interfilar substance, showing that the 

 radial striae of the chorion are due originally to protoplasmic fibers. 



Fig. 14. Section of an egg about to be discharged into the ovarian tube, 

 showing the movement of the germinal vesicle and its relation to the " Kernpol " 

 area. 



Fig. 15. Section of an adult ovarian tube, showing the folding of the germinal 

 epithelium and with it the tunica propria, t.p.; the variable size and form of the 

 epithelial cells ; the formation of empty follicles, /., by evagination through the 

 fenestrae of the muscle coat, m.c.\ the relation of the number and size of the eggs 

 to the number of empty follicles ; the position of the immature eggs with refer- 

 ence to the empty follicles and the point of attachment of the tube ; the relation 

 of this latter to the enclosing peritoneal coat, f r. 



