. Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania, vol. 13. Botany; Botany. I I. July, 1936] ANDERSONâMITOCHONDRIA 499 If ; â MicT()i)ylar end of maturo oml>ryo sac of Anlirrhunim, with surrounding nucoUus; (a) synorjiul, (h) ffiir. (r) fused i)olar nurloi.âFig. 23. Kinhryo sac of Antinhhnnn just aftor tho i)()ll('n lul)e has ruptured. ()no nialo nucleus (/>) has ontcrrd tho ogg leaving an opening in tho niomhrano. Tho other male nucleus is migrating throiigh the cytoi>lasm of the embryo sac to the fused jiolar


. Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania, vol. 13. Botany; Botany. I I. July, 1936] ANDERSONâMITOCHONDRIA 499 If ; â MicT()i)ylar end of maturo oml>ryo sac of Anlirrhunim, with surrounding nucoUus; (a) synorjiul, (h) ffiir. (r) fused i)olar nurloi.âFig. 23. Kinhryo sac of Antinhhnnn just aftor tho i)()ll('n lul)e has ruptured. ()no nialo nucleus (/>) has ontcrrd tho ogg leaving an opening in tho niomhrano. Tho other male nucleus is migrating throiigh the cytoi>lasm of the embryo sac to the fused jiolar nuclei (c). Other .<<tructures .shown are (a) pollen tul);(r) synergid. {d) egg nucleus, (/) antipodals.âFig. 24. Enilnyo sac of Anlirrhhuim immediately after fertiliza- (i()â ; 25. Mature itollen grain of 11 uartifization. showing endosi)erm (6), and zygote (a) which has not yet divided. X 412.âFig. 27. Young emlnyo showing first di\ ision of fertilized egg nucleus. The endosperm is not shown. X 1050. i 49S 4'JU actions and in form from of the egg, they can- not be distinguished from the latter once they have entered the egg. If the cytoplasm with some of its passes into the egg along with the male nucleus, Correns' original exi)lanation of maternal inheritance will have to be abandoned, and the of the failure of the pollen to transmit these plastid deficiencies will have to lie sought elsewhere. In some forms (Zea, Oryza, Hosta, etc.) only two tyjies of plants reach maturity, those which are variegated and normally green. The lighter jilants die. The variegated plants iiro- duce a certain amount of normal jiollenâ, ])ollen without any defective plastitls. When the flower is pollinated with a mixture of normal and defective pollen, selective fertilization could exjilain the failure of the male parent to the defect. It is evident that only a few mitochondria enter the egg with the male nucleus. They


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