the Grain of Wheat ( Triticum vulgare). 
139 
EXPLANATION OF FIGURES IN PLATES VIII AND IX. 
Illustrating Miss Brenchley’s Paper on the Grain of Wheat. 
Abbreviations used: 0. ovum; sy. synergid ; g.n. generative nucleus; e.n. endosperm nuclei; 
e.s. embryo sac ; p.t. pollen tube ; d. deeply-staining bodies in pollen tube ; ep. nuc. limiting 
layer or nuclear epidermis ; ov. integ. ovular integuments ; pi. placenta ; pc. pericarp ; nuc. 
nucellus ; end. endosperm ; si. end. starchy endosperm ; a.l. aleurone layer ; st. starch grains ; 
sc. ordinary cells of scutellum ; v.s. conducting strand in scutellum; m. micropylar end of e.s. ; pm. 
protoplasm of e.s. ; emb. embryo ; f. furrow of grain ; r. radicle ; f.l.r. first pair of lateral rootlets ; 
s.l.r. second pair of rootlets; f.r. fifth rootlet; c. cotyledon; f.l. first leaf; s.l. second leaf; w. 
germinating wheat grain ; T.S. transverse section ; L.S. longitudinal section. 
PLATE VIII. Figs. 1-16. 
Fig. 1. Rather oblique section through embryo-sac about two days after pollination. Enclosed in 
the ovum is a dark mass which probably is the male generative nucleus which has not yet lost its 
individuality. Two nuclei are present at the other side of the sac, the result of the first division of 
the definitive nucleus, x 2 70. 
Fig. 2. The adjacent section to Fig. 1, showing the tip of the pollen tube overlying the ovum, 
x 260. 
Fig. 3. Part of T.S. of e.s. three days after pollination. The cells of the nucellar epidermis 
have renewed their activity and the nuclei are in process of division, x 270. 
Fig. 4. Part of L.S. through e.s. six days after pollination, showing the numerous endosperm 
nuclei embedded in the protoplasmic lining which surrounds the central vacuole, x 170. 
Fig. 5. L.S. through e.s. seven or eight days after pollination. Cell wall formation is proceeding 
inwards from the periphery of the endosperm, but the cells are not complete in the middle, x 1 70. 
Fig. 6. Part of T.S. of grain eight days after pollination. Remains of the thin-walled nucellus 
still occur between the nucellar epidermis and the endosperm, x 270. 
Fig. 7. T.S. ten days after pollination. Thin-walled nucellus has entirely disappeared, x 270. 
Fig. 8. T.S. fourteen days after pollination. The nucellar epidermis is losing its cell contents, 
and the outer layer of the endosperm is marked out to form the future aleurone layer, x 270. 
Fig. 9. T.S. nineteen days after pollination. Aleurone layer clearly marked out. x 270. 
Fig. 10. T.S. of mature grain, showing endosperm fully developed, x 270. 
Fig. 11. T.S. Perfect endosperm nuclei, with nucleoli, x 320. 
Fig. 12. T.S. Endosperm nuclei rather deformed by pressure ; no nucleoli, x 320. 
kig. r 3 * L.S. Endosperm nuclei in 4 coarse network ’ stage, x 320. 
Fig. 14. T.S. Endosperm nuclei in ‘ fine network’ stage, x 320. 
Fig* I 5 ‘ L.S. of scutellum one week before the com was cut, showing the conducting strand 
just after it has turned out from the hypocotyl — cells roughly hexagonal in T.S. Cell contents omitted, 
x 180. 
Fig. 16. Same embryo as Fig. 15, showing conducting strand at a point lower down the grain, 
where the cells are elongated in T.S. On one side the strand is just beginning to spread out 
laterally. Cell contents omitted, x 180. 
PLATE IX. Figs. 17-23. 
Fig. 17. Same embryo as Fig. 15, but lower down than Fig. 16, where the conducting strand 
has spread out in a fan-like manner. Cell contents omitted, x 180. 
Figs. 18-23. Six successive stages in germination, showing the order of development of the 
rootlets. About natural size. 
N.B. — In Figs. 4, 5> 6, 7 the endosperm has somewhat shrunk away from the surrounding 
tissues in the course of preparation. 
