CHANGES IN REPRODUCTIVE CELLS OF ELASMOBRANCHS. 313 
Fig. 62.—Daughter-cells of first heterotype division, with vestigial fla- 
gellum, showing cystoplasmic condensation about the sphere. 
Fic. 63.—Daughter-cells of first heterotype division, with vestigial fla- 
gellum, showing cytoplasmic condensation about the sphere. 
Fig. 64.—Daughter-cells of first heterotype division, with vestigial fla - 
gellum, showing cytoplasmic condensation about the sphere. 
Fic. 65.—Initial stage of final division. 
Fie. 66.—The same later. 
Fie. 67.—The same later, showing divarication of the centrosomes at the 
cell periphery. 
Fie. 68.—Complete formation of chromosomes of the final heterotype. 
Fie. 69.—Monastral spindle figure. 
Fig. 70.—Monastral spindle figure, polar view. 
Fies. 71—78.—Successively later stages of final heterotype division. 
Fic. 79.—Daughter-cells of the final heterotype, showing translation of the 
spheres, and initial stages of tail formation. 
Fics, 80—81.—Successively later stages of the same. 
Fie, 82.—Cells showing the origin of the archoplasmic vesicle, and peculiar 
form of nucleolus. 
Fic. 83.—Cells showing the origin of the archoplasmic vesicle, and peculiar 
form of nucleolus ; showing elongation of the intra-cellular part of the flagel- 
lum, and the attachment of the archoplasmic vesicle to the nuclear wall. 
Fic. §4.—Cells showing the origin of the archoplasmic vesicle and peculiar 
form of nucleolus; showing elongation of the intra-cellular part of the flagel- 
lum, and the attachment of the archoplasmic vesicle to the nuclear wall. 
Fie. 85.—Cells showing the origin of the archoplasmic vesicle and peculiar 
form of nucleolus ; showing elongation of the intra-cellular part of the flagel- 
lum, and the attachment of the archoplasmic vesicle to the nuclear wall; 
showing position of the archoplasm, and re-formation of ring chromosomes, 
Fics. 86—87.—Two views of the tail during its passage away from the 
archoplasmic vesicle. 
Fies. 88—90.—Successive stages in the elongation of the spermatozoids. 
Fie. 91.—Optical section of spindle in first heterotype division, showing 
outer and inner spindle tubes, o. s., 7. s. 
