ob 
Ox 
G 
Fic. 64.— Behavior of chromosomes during maturation, fertilization, 
and cleavage of Ancyracanthus cystidicola. (From Mulsow, 1918.) 
A. Spermatogonium with eleven chromosomes. B. First matura- 
tion (spermatocyte) division. The single chromosome finally joins 
one group. C. The four spermatids arising from one spermatocyte ; 
two with six chromosomes, and two with five. D. Two spertna- 
tozoa drawn while alive; one with six chromosomes, and one with 
five. E. Odgonium with twelve chromosomes. F. Second matura- 
tion (odcyte) division. The black mass above is the first polar 
body; the set of six black chromosomes are those of the second 
polar body; the six dotted chromosomes are those of the egg. 
G. Fertilized (male producing) egg; sperm nucleus above with five 
chromosomes; egg nucleus below with six chromosomes. dH. Fertil- 
ized (female producing) egg; both egg and sperm nuclei with six 
chromosomes. J. Cleavage stage of male producing egg; the central 
cell with nucleus containing eleven chromosomes. J. Cleavage 
stage of female producing egg; the lower cell with nucleus contain- 
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