8G If; B. Kirkhmn— Maturation of the Egg of the White 3fouse. 



Plate II. 



Figure 0. — Ovarian egg ; showing first polar sijindle in paratangential position. 

 A minute eentriole appears at the right-hand pole of the spindle, while 

 three similar bodies are visible at the opposite focus. The chromosomes 

 are t^^ijic.al tetrads. x 14o0. 



Figiire 4. — (Ovarian egg ; showing a first polar spindle in a positiuu approach- 

 ing radial, x 1450. 



Plate III. 



Figure 5. —Egg in Graafian follicle ; showing first polar body and second polar 

 spindle. x 560. 



Figure 0. — Same egg at greater magnification. Seventeen masses of chromatin, 

 some of which are iindivided dyads, are scattered through the first polar 

 body among traces of spindle fibers ; twenty-four univalent chromosomes 

 appear in the equatorial plate of the second polar spindle. Certain chro- 

 mosomes have been added from adjacent sections. Minute centrioles 

 appear at each pole of the second spindle, x 1450. 



Plate IV. 



Figure 7. — Ovarian egg ; showing second polar spindle and an abnormally large 

 first polar body. Note spindle in polar body, and twenty-four filiform, 

 imivalent chromosomes in the egg. x 1450. 



Figure 8. — Ovarian egg ; showing first polar body and second polar spindle. 

 Two minute centrioles appear at each pole of the second sjjindle. The 

 chromatin in the polar body is at the telophase of mitotic division. x 1450. 



Figure 9. — Portion of ovarian egg ; showing first polar body. Note constric- 

 tion in middle of polar body, the beginning of the final step in mitotic 

 division, x 1450. 



Plate V. 



Figure 10. — Ovarian egg ; showing second polar sjiindle. First polar body 

 omitted. Note radiating fibers at inner pole of spindle, and lateral fibers 

 at outer end. (The position of the spindle in the egg is slightly diagram- 

 matic.) X 1450. 



Figure 11. — Egg in Graafian follicle, in which the zona has disappeared, proba- 

 bly through the solvent action of reagents. Egg and polar body have 

 separated from coronal cells, and lie free in liquor folliculi. Second polar 

 spindle is visible near the perijihery of the egg. x 560. 



Plate VI. 



Figure 13. — Egg in Fallopian tube ; showing second polar spindle. First polar 

 body has disappeared. Egg has not yet been fertilized, x 1450. 



Figure 13. — Two eggs in Fallopian tube, surrounded by cells of the membrana 

 granulosa. Note the nearness of the eggs to each other. Upper egg shows 

 the female pronucleus. Lower egg shows two typical polar bodies. The 

 greater part of the chromatin of the first polar body is in adjacent sections. 

 But it all appears as separate chromosomes, while that in the second polar 

 body is collected into a fairly solid mass. Note the ragged and imperfect 

 zona pellucida, a condition due in part to the solvent action of reagents. 

 X 560. 



