242 Morphologie etc. — Varietäten etc. 



The fully grown macrospore mother cell lies in either the third 

 or fourth layer from the micropylar end of the nucellus. 



An axial row of three macrospores is formed, the innermost of 

 which develops into the embryo-sac. 



The nucellus is entirely destroyed at the micropylar end and 

 along the sides by the development of the embryo-sac; the nucellar 

 tissue at the base of the sac takes on a peculiar structure and 

 persists for some time, but finally is itself gradually absorbed by 

 the embryo sac. 



The polar nuclei begin to approach each other soon after the 

 eight-nucleate stage of the embryo-sac is reached and remain close 

 together for some time just below the egg; then their fusion takes 

 place. 



The three antipodal cells disappear at about the time of fertili- 

 zation. 



The synergids form a conspicuous filiform apparatus. 



The pro-embryo consists of a filament of three cells; the two 

 basal cells form the suspensor and the terminal cell develops into 

 the embryo proper. 



. The dermatogen is cut off when the embryo proper consists of 

 about sixteen cells. When the suspensor consists of four rows of 

 about seven or eight cells each, the two tiers of cells at its base 

 become swollen and conspicuously elongated. 



The primary endosperm nucleus usually divides before the 

 first division of the egg; two of the daughter nuclei resulting from 

 the first two divisions place themselves on either side of the young 

 embryo; and in succeeding divisions the endosperm nuclei place 

 themselves in the peripheral region of the embryo sac. 



The divisions of the endosperm nuclei may be simultaneous, or 

 nuclei in all stages of division may be found at the same time, 

 from resting nuclei at one end of the endosperm to late telophases 

 al the opposite end. 



Endosperm cells are formed in the region immediately about 

 the embryo, but are later absorbed. Jongmans. 



Ikeno, S., Etüde gen£tique sur les aretes d'une race de 

 l'Orge ä six rangs. (Bot. Mag. Tokyo. XXXI, p. 263—267. PL 

 II, III. 1 fig. 1917.) 



Une race japonaise de V Hordetim sativum hexastichum, connu 

 par le nom vulgaire „Kinukawa" a tous ses epillets tres grelement 

 aristes, bien que les aretes de ceux appartenant au rang moyen 

 soient quelque peu plus longues que Celles appartenant au rang 

 lateral. 



Pour etudier l'h^redite de ces aretes, M. Ikeno a fait un croise- 

 ment de cette race avec une autre aussi bien ä six rangs, appelee 

 vulgairement: „Nogenasi", oü les aretes fönt en general defaut. 



Les resultats de ses experiences ont €te resumes par l'auteur 

 comme suit: On a affaire ä trois facteurs A, E, I, dont les deux 

 Premiers sont renfermös dans le parent ariste Kinukawa et le 

 dernier se trouve dans le parent mutique Nogenasi. Meme sans 

 aucun de ces trois facteurs les aretes moyennes et laterales courtes 

 peuvent etre developpees, mais en presence de Tun des deux fac- 

 teurs, soit A, soit E, les aretes sont plus longues et en presence 

 simultanCe de tous les deux elles peuvent croitre jusqu' ä une 



