ZEA MAYS 139 



mature endosperm are approximately fifty times that of its initial 

 stage. This growth is accomplished by a general cell division of 

 the parenchymatous cells; but, later, there is a localization of this 

 activity to the peripheral region of the endosperm. The outermost 

 layer of the endosperm, which forms the aleurone zone, exhibits 

 certain epidermal characteristics; and, after about three weeks, 

 divides only anticlinally. The subepidermal cells may continue to 

 divide until the embryo is mature and are consequently smaller than 

 the aleurone cells. 



The Antipodal Tissue. — The persistence of antipodal tissue 

 has been noted by Weatherwax (x}) and Randolph (15). In many 

 grasses, the antipodals are reported as disintegrating during the 

 formation of the endosperm; but in corn, this haploid tissue (10 

 chromosomes) persists until the caryopsis is mature. It occupies 

 a position near the micropyle during the early ontogeny; but as 

 the endosperm enlarges is displaced and comes to occupy a region 

 in the crown of the kernel. At maturity, the antipodal tissue con- 

 sists of hundreds of cells, which are packed with starch, surrounded 

 by an epidermis that is starch-free. 



LITERATURE CITED 



I. Avery, G. S., Jr., "Comparative anatomy and morphology of embryos and 



seedlings of maize, oats and wheat." Bot. Gaz- Sp: 1-39, 1930. 

 z. DE Bary, a., Comparative Anatomy of the Vegetative Organs of Phanerogams and 

 Ferns, Clarendon Press, Oxford, 1884. 



3. Campbell, D. H., "On the development of the stomata of Tradescantia and 



Indian corn." Am. Nat. i;: 761-766,1881. 



4. Celakovsky, L. J., "Uber die Homologien des Grasembryos." Bot. Zeit. //.• 



141-174, 1897. 



5. Collins, G. N., "Structure of the maize ear as indicated in Zea-Euchlaena 



hybrids." Jour. Agr. Res. 17: 117-135, 1919. 



6. Evans, A. T., "Vascularization of the node in Zea mays." Bot. Gaz. ■?/•' 



97-103, 19x8. 



7. GuiGNARD, L., "La double fecondation dans le mais." Jour, de Bot. //.• 



37-50, 1901. 



8. Harshberger, J. W., "Maize, a botanical and economic study. Contr. Bot. 



Lab. Univ. Pa. i: 75-101, 1893. 



9. Hershey, H. L., and Martin, J. N., "Development of the vascular system of 



corn." Proc. Iowa Acad. Sci. }j: 115-116, 1930. 

 10. Miller, E. C, "The development of the pistillate spikelet and fertilization 

 in Zea mays L." Jour. Agr. Kes. 18: i.'^'^-i.Gj, 1919. 



II. Montgomery, E. G., "Perfect flowers in maize." Pop. Sci. Monthly 79: 



346-349, 1911. 



