308 



Fig. 3. a. R. (Coriifoliae) Mafssonii At. Metaphase stage in the embryo-sac motlier 

 cell. The 7 bivalents next to the chalaza, the 21 singles next to the niicropyle. 

 b. M. (Caninae) oblonga Rip. Embryo-sac mother cell after the heterotypic division. 

 In the micropylar nucleus 28 chromosomes (7 partners of the bivalents plus all 

 the singles), in the chalazal nucleus only 7 (partners of the bivalents). c. R. 

 (Coriifoliae) *hirfi-grossidens At. Teträd consisting of two great micropylar mega- 

 spores probably containing 28 chromosomes in tlieir nuclei aud two small chalazal 

 megaspores probably with 7 chromosomes in the nuclei. — For a and b, obj. 

 Leitz J-, ocular 18: for e, obi, Leitz -^, ocular 18; all reduced one-fourth in 



16' ' ' •■ IJ 



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 soinetunes less) should, if the latter 



