CHANGES IN REPRODUCTIVE CELLS OF ELASMOBRANCHS. 811 
evolved ; and whatever the synapsis may eventually turn out 
to be, it is evidently a cellular metamorphosis of a profoundly 
fundamental character, which would appear to have been 
acquired before the animal and vegetable ancestry went apart, 
and to have existed ever since. 
In conclusion, I would express my sincere thanks to Prof. 
Howse for much help, and to the Royal College of Science 
for granting me the Marshall Scholarship for the completion 
of this investigation. 
DESCRIPTION OF PLATES 138—16, 
Illustrating Mr. J. E. S. Moore’s paper, “On the Structural 
Changes in the Reproductive Cells during the Spermato- 
genesis of Elasmobranchs.” 
REFERENCE LETTERS. 
a. Archoplasm. 6.c. Chromatic body. c¢. Centrosome. c.f, Foot-cells. 
ch. Chromosomes. c.s. Seminiferous cells. 4.7. Flemming’s intermediate 
bodies. fr. Fragmented portions of foot-cells. 2. Linin filaments. m. 
Mittelstiick, and portion of flagellum contained in it. %. Nucleolus. x.y. 
Nuclear groove. z.v. Nuclear sap-spaces. i.s. Inner spindle-sheath. 0.. 
Outer spindle-sheath. 7. Cytoplasmic radiations round the sphere. f. Fla- 
gellum. z. Indeterminate body at the base of the flagellum. 
The figures were drawn with Zeiss’? hom. immer., 2 mm., 140 ap., and 
oculars 12, 18, except Figs. 1, 3—10. 
Cells of the first spermatogenetic period. 
Fic. 1.—Single primitive cells from which the contents of the ampulle are 
formed, 
Fic. 2.—Single seminiferous cell, of the first spermatogenetic period. 
Fig. 3.—Early relative position of seminiferous and foot-cells. 
Fie.4.— Do. do. with foot-cell in division. 
Fie. 5.— Do. do. later. 
Fig. 6.—Fragmentation of foot-cells. 
