IO 2 EDWARD DRANE CRABB. 



PLATE 3. 



All figures except 19 are from virgin eggs. Figs. 19 to 25 were drawn 

 to the scale of 0.03 mm., PI. 4; Figs. 17, 18, to 0.04 mm. 



FIG. 17. Four-cell stage from the hermaphrodite duct. Zenker 40 C, 

 55 minutes, 7 n, iron-haematoxylin. 



FIG. 18. A later cleavage stage from an acinus (region H, Fig. i, Crabb, 

 '27^). Modified Flemming, 8 M, iron-hsematoxylin. 



FIG. 10. Reconstructed from two consecutive sections of an ovum de- 

 posited in the sperm receptacle during copulation. The piece of sperm tail 

 and its vesiculated head are on one section, the archiamphiaster is on the 

 other. Modified Flemming, 8 M, iron-hsematoxylin. 



FIG. 20. Reconstructed from two consecutive sections of an egg before 

 the second polocyte is extruded, showing the vesiculated sperm head and 

 its aster. Modified Flemming, 10 /", iron-haematoxylin, Gage's acid fuchsin. 



FIG. 21. Reconstructed from three consecutive sections of a freshly laid 

 egg showing first maturation spindle, sperm head and tail. The sperm head 

 is more vesiculated than is usually found in eggs after the first maturation 

 division. The piece of sperm tail is not stained. No asters could be seen. 

 Modified Flemming, nitric acid solution, 6 A 4 , iron-hsematoxylin. 



FIG. 22. Reconstructed from the first and fourth of four consecutive 

 sections of an egg which has recently given off the first polocyte. The 

 vesicle-like sperm head is at a lower level than its aster. Modified Flem- 

 ming, nitric acid solution, IOA*, iron-hsematoxylin. Gage's acid Fuchsin. 



FIG. 23. Reconstructed from three consecutive sections of an egg which 

 has given off the first polar body, showing sperm amphiaster forming. 

 Modified Flemming, 6 AS iron-haematoxylin. 



FIG. 24. An egg after the first maturation division showing the vesicu- 

 lated sperm head and an aster. Fixed one hour and twenty minutes after 

 being oviposited. Modified Flemming, 4 /*, iron-hsematoxylin. 



FIG. 25. An early stage in the formation of sperm karyomeres. The 

 egg chromosomes are somewhat vesiculated, but the second polocyte has 

 not been extruded. Modified Flemming, 4 M, iron-haematoxylin. 



