Maturation and Fertilization in Theridium. 249 



Explanation of Plates. 



All the drawings were made with the camera lucida, and unless 

 otherwise specified were dra^^^l from sections. 



(J sperm nucleus Pol. 2 second polar body 



$ egg nucleus Rec receptaculum seminis 

 Ap exterior opening to receptaculum S. Cyt superficial layer of cytoplasm 



seminis Sp sperm nucleus 



C. Mb cell membrane Spi. 1 first polar spindle 



Cijt cytoplasm T. 1 external tube of receptaculum 

 Egg. N egg nucleus seminis 



Mem outer egg membrane T. 2 internal tube of receptaculum 

 PI plasmosome seminis 



Pol. 1 first polar body 



Plate 4. 

 Fig. 1. Nucleus of late follicular egg. 200 : 1. 



Figs. 2a, 2b. Consecutive sections of the chromosome complex of 

 Fig. 1. 2400 : 1. 



Fig. 2c. Deep staining rod from the same nucleus. 2400 : 1. 



Fig. 3. Outline of an egg illustrating the two yolk layers. 100:1. 

 ca. 1 hour. 



Fig. 4. Optical section of the surface of an egg to show the columnar 

 yolk layer, ca. 1 hour ; the first pole body there represented really lies 

 on the surface at much higher focus and is given merely to show its 

 proportionate size. 500 : 1. 



Fig. 5. Portion of the surface of an egg at oviposition. 1800 : 1. 



Fig. 6. An egg at oviposition to show positions of the sperm nucleus 

 and the first polar spindle. ,100 : 1. 



Fig. 7. First polar spindle at oviposition. 2400 : 1. 



Fig. 8. Sperm nucleus and surrounding cytoplasm at oviposition. 

 2400 : 1. 



Fig. 9. Superficial portion of first polar spindle at 5 minutes. 2400: 1. 



Fig. 10. Surface view of chromosomes of the first polar body, 1 hour. 

 1800 : 1. 



Figs. 11 — 13. Surface views of first polar bodies, at ages of 1, 1^/^ 

 and 1^/2 hours respectively. 1800 : 1. 



Fig. 14. First polar body, P/^ hours. 2400: 1. 



Fig. 15. Surface view showing second polar spindle to the right 

 and chromosomes of the first polar body to the left, 40 minutes. 1800: 1. 



