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308
Fig. 3. a. R. (Coriifoliae) Matssonii At. Metaphase stage in the embryo-sac mother
cell. The 7 bivalents next to the chalaza, the 21 singles next to the micropyle.
b. R. (Caninae) oblonga Rip. Embryo-sac mother cell after the heterotypie division.
In the micropylar nucleus 28 chromosomes (7 partners of the bivalents plus all
the singles, in the chalazal nucieus only 7 (partners of the bivalents). c. R.
(Coriifoliae) *hirti-grossidens At. Tetrad consisting of two great micropylar mega-
spores probably containing 28 chromosomes in their nuclei and two small chalazal
megaspores probably with 7 chromosomes in the nuclei. — For a and b, obj.
ocular 18; for c, obj. Leitz ;’, ocular 18; all reduced one-fourth in
,
Leitz 3,
reproduction.
18. A cross between a gallica (x — 14) and a pentaploid species
of the section Caninae (in the pollen grains 7 to about 15 chro-
mosomes, in the eggs 28 or sometimes less) should, if the latter
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