Pboc. Kot. Soc. Victoria 34 (N.S.), Pt. II., 1922]. 



Aht. XIII. — The Development of Endosperm in Cereals^ 



By MARY GORDON, B.Sc. 

 (Caroline Kay Scholar). 



(With 9 Text Figures.) 



[Read 13th October, 1921]. 



The early stages of endosperm development are accurately- 

 described in the text-books and other publications dealing with 

 the subject; but it is assumed that the process of free cell- 

 formation, by which the first layer of endosperm arises, is- 

 continued throughout the development of the seed, and that 

 all the endosperm cells are formed by the development of cell- 

 walls around the nuclei that lie freely in the protoplasm of the 

 embryo-sac. The earlier stages in the development of the 

 endosperm of Burmannia — a monocotyledon comparable with, 

 the cereals in endosperm development — have been described by 

 Ernst and Bernard (i). They have shown that the nuclei formed 

 by the division of the first endosperm nucleus, do not become 

 immediately enclosed in cell-walls, but they line the embryo-sac^ 

 and later cell-walls develop between them. From this stage 

 Ernst and Bernard did not trace the method of endosperm-, 

 development any further; they apparently took for granted 

 that all the endosperm was formed in a similar manner. 



The mature grains of cereals agree in the main points of 

 structure, having the bulk of the endosperm composed of large 

 cells filled with starch grains, and a peripheral layer, or layers, 

 in the case of barley, containing no starch, but protein material 

 in the form of aleurone grains. These cells also contain large 

 nuclei, whereas the nuclei of the inner cells are much dis- 

 organised. 



In a paper — ^The Endophytic Fungus of Lolium — published 

 in the proceedings of the Royal Society of Victoria, Dr. 

 McLennan (2) has described the outer layer of the endosperm 

 of Lolium iemukntum as an endospermic cambium, which in- 

 active only on its inner surface, where it cuts ofif brick-shaped 

 cells which assume an approximately spherical form as they 

 attain their adult size. They remain thin-walled and constitute 

 the starchy endosperm. As the grain approaches maturity, the 



