216 Maine Agricultural Experiment Station. 1920. 



List of Illustrations. 



Figure 33. Lolium italicum. Surface view of the epidermal cells in 

 the middle section of the lemma. K, Kj, silicious cells ; iK, isolated sili- 

 cious cell. 



Figure 34. Lolium italicum. Basal part oi the lemma showing epi- 

 dermal cells in the region where the coleorhiza broke through. Note 

 the initiation of a longitudinal slit along cell i. 



Figure 35. Lolium italicum. A, a layer of sclerenchymatous cells 

 in the middle section of the lemma; B, sclerenchymatous cells at the base 

 of the lemma where the coleorhiza broke through; C, single sclerenchy- 

 matous cell ; b, bj, short cells severed from the base of the lemma. 



Figure 36. Festuca arundinacea. Part of transverse section through 

 the base of the lemma, below the region where the coleorhiza breaks 

 through ; ae, outer epidermis ; h, prosenchyma ; p, parenchyma. 



Figure 37. Festuca arundinacea. Part of transverse section through 

 the lemma in the region where the coleorhiza breaks through, ae, outer 

 epidermis ; h, prosenchyma ; p, parenchyma ; ie, inner epidermis ; g, lateral 

 fibrovascular bundle. 



Figure 38. Festuca arundinacea. Transversal section through the 

 lemma above the line of rupture, representing the part between the lateral 

 and marginal fibrovascular bundles, ae, outer epidermis ; ps, prosen- 

 chyma ; p, parenchyma ; ie, inner epidermis ; K, silicious cell. 



Figure 39. Alopecurus pratensis. Abnormal germination: The rad- 

 icle pushed the germinating caryopsis out of the sterile and fertile glumes. 

 K, caryopsis; r, radicle; col., coleorhiza; c, coleoptile ; pb, plumule; Kl, 

 sterile glumes. 



Figure 40. Holcus lanatus. Abnormal germination : A, ' the cary- 

 opsis is raised in the sterile glumes with the radicle appearing at their 

 tip. B, the germinating caryopsis, K, after removal of sterile glumes. 

 After normally breaking through the lemma, the radicle, r, grew upward 

 along the sterile glume ; c, coleoptile ; dk, lemma : vs, palet. 



Figure 41. Hordeum sativum. Longitudinal section through apical 

 part of the coleorhiza. The upper delicate elliptical cells become thicker 

 toward the apex and terminate by thick-walled cells of the apical appen- 

 dage. 



Figure 42. Festuca arundinacea. Surface view of the expanded api 

 cal appendage. 



Figure 43. Polyembryony in Poa pratensis. K, caryopsis ; r, r lt ab- 

 normally extending radicles ; c, c lt coleoptile* ; p, p lt plumules ; ds, lemma ; 

 vs, palet. 



Figure 44. Polyembryony in Arrhenatherum elatius. K, caryopsis; 

 r, r„ radicles pushing the seedling out of the glumes ; c, c 1; the two 

 equally favored coleoptiles ; col, col 1; coleorhizas ; sp, fertile glumes. 



