. Maïs ; son histoire, la culture, la manutention, et utilise, avec référence spéciale à l'Afrique du Sud ; un texte-livre pour les agriculteurs, les étudiants et les enseignants de l'agriculture, de l'étude de la nature. Maïs, maïs. Caractères BOTANIQUES T07 *"d avec le noyau de l'ovule pour former l'embryon (Fig. 54) ; la fécondation est alors accompli. L'autre noyau mâle fusionne avec les deux noyaux polaires femelles ; à partir de ces l'endosperme est développé. La croissance cellulaire et la division cellulaire, et sont ensuite commencer a continué jusqu'à la graine mûre est développé. Les chromosomes du maïs sont petites et difficiles à étudier, et à peine anythi

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. Maize; its history, cultivation, handling, and uses, with special reference to South Africa; a text-book for farmers, students of agriculture, and teachers of nature study. Corn; Corn. BOTANICAL CHARACTERS T07 *»d with the nucleus of the egg-cell to form the embryo (Fig. 54); fertilization is then accomplished. The other male nucleus fuses with the two fused female polar-nuclei; from these the endosperm is developed. Cell-growth and cell-division then commence, and are continued until the mature seed is developed. The chromosomes of maize are small and difficult to study, and scarcely anything is known of their behaviour during the maturation division {East, 6). 79. Dichogamy.— According to Kerner (1), most moncecious plants, including maize, are proto- gynoits, i.e. the female flowers are receptive before the pollen of the same plant is shed, thus necessitat- ing cross-pollination. Ifprotogyny were complete, the very first plant in a field, which developed female flowers, would, in consequence, fail to propagate its kind, unless accidentally pollinated from a still earlier plant in a neighbouring field ; but there would always be oiie plant in a district that was earliest of all, and which would therefore fail to develop grain. This habit would act to some extent as a check to any natural tendency to increased earliness in maturity. If all the plants in a field flowered on exactly the same day, and all were completely protogynous, there would be no pollination except from other and earlier-planted fields, and those of the first planting would always fail to develop grain. But this is not the case. As already pointed out (If 72), there is a great difference in time of flowering with individuals in the same field, due to many causes, e.g. individual characteristics, difference in depth of planting, variation in soil fertility, soil texture and soil moist- ure, etc. The flowering period in any one field or plot may thus extend over ten days or three weeks.. Fig.

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