300 



Ethel McLennan : 



Plate XXIV. 



A portion of the endosperm from a nearly mature grain. The- 

 outer layer is being transformed into the aleurone layer, but even 

 at this stage liyphae are entering the cells, and are being absorbed 

 by them. The aleurone layer is cut tangentially in the upper 

 part of the grain; tlie layer therefore, appears several cells, 

 thick at this point. The starchy endosperm cells immediately 

 uncLerneath the nitrogenous containing ceils show well-marked 

 nuclei, but these will disappear as the grain reaches maturity. 



(a) aleurone layer; (g) young aleurone grain; (p) protoplasmic 

 network in aleurone cells; (h) hyphae accumulating to form a 

 layer; (et) hyphae entering aleurone cells; (n) nuclei of aleurone 

 layer; (s) starch groups; (ne) nuclei of endosperm cells, x 1100' 

 diam. 



Plate XXV. 



Figs. 



different 

 Fig. 1.- 



Fig. 2.- 

 Fig. 3.- 

 Fig. 4. 



Fig. 5.- 



1-5 illustrate the relation of the fungus and embryo at 

 stages ini the development of the grain. 



-Endosperm cells from the embryonic pocket drawn from, 

 the same slide as Fig. 2. The fungus occurs in great 

 abundance in this region at this stage. It is being 

 used by the endosperm, which in turn hands on the food 

 material to the embryo. 



(h) hyphae; (e) endosperm cells of embryonic pocket;, 

 (e^) ordinary endosperm cells, x 625 diam. 

 -A young embryo. 



(e) endosperm cells being used by the embryo as food;, 

 (h) hyphae; (s) suspensor end of embryo, x 625 diam. 

 -An older embryo, the endosperm cells at the proximal. , 

 end of the pocket have disappeared. 



(h) hyphae present in embryo, x 625 diam. 

 -An embryo showing differentiation of scutellum, and 

 growing point. Stained densely with congo red, so that 

 hyphae in growing point could not be seen. 



(h) hyphae at suspensor end; (g) growing pt. ; (s)/ 

 scutellum. x 300 diam. 

 -Ihe tip of the scutellum from a grain of Lolium perenne 

 (not yet fully developed), which did not contain an extra 

 cellular hyphal layer in the usiial position. Hyphae were- 

 present, however, in the scutellum and embryo. 



(s) scutellum; (e) epithelial layer; (h) hyphae. x 500' 

 diam. 



