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. 

 h. R. (Caninae) oblonga Rip. Embryo-sac mother cell after the heterotypic division. 

 In the micropylar nucleiis 28 chroniosomes (7 partners of the bivalents plus all 

 the singles;, in the chalazal nucleus 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 probabl}^ with 7 chromosome.s in the nuclei. — For a and b. obj. 

 Leitz j\, ocular 18; for c, obj. Leitz jV,, ocular 18; all reduced one-fourth in 



reproduction. 



18. A cross belween a gallica {x = 14) and a pentaploid species 

 of the seclion Caninae (in the pollen grains 7 to aboiit 15 chro- 

 mosomes, in the eggs 28 or sometimes less) should, if the ialler 



