THE ENDOSPERM 



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Cytological Make-up of the Endosperm 



Since, in the basic Polygonum type of embryo sac, the nuclei entering 

 into the triple fusion are haploid, the primary endosperm nucleus and 

 all cells developed from it are triploid. The endosperm in the Allium 

 and Adoxa types is also triploid. It is diploid in the Oenothera type and, 



Fig. 116. Early stages in development of embryo and cellular endosperm in Ccrcidi- 

 phyllum. A, B, embryo sac, enlarged after fertilization, with zygote, vestigial anti- 

 podals, and two walled endosperm cells; C, D, E, successive stages in formation of 

 the endosperm, the z)gote still unicellular; F to K, stages in development of the 

 embryo. (After Swatmj and Bailey.) 



in the other types, polyploid, varying in its chromosomal make-up. In 

 the Fritillaria and Plumbagella types, one of the polar nuclei is triploid 

 and, in the Peperomia, Penaea, and Plumbago types, more than two 

 embryo-sac nuclei enter into the primary endosperm nucleus. 



The endosperm is a food-storage tissue, usually of simple structure; 



