298 Ethel McLennan: 



Plate XX. 



A longitudinal section of an ovary of Loliu^m perenne^ just prior 

 to fertilisation; stained with bismarck brown, then with gentian 

 Tiolet, followed by Gram's wash. 



(c) carpel wall; (s) starch groups in cells of carpel wall; (i) in- 

 vaded cells at stalk end of section; (h) hyphae in stalk of ovary; (h^) 

 hyphae in distal part of wall; (h") hyphae in distal part of wall 

 not staining with gentian violet; (t) cells in stigmatic tract being 

 used by the fungus as food; (ov) ovule; (hy) hyphae distributed in 

 all parts of ovule; (ic) infected cells of ovule; (es) embryo-sac; \p) 

 ovum; (hyi) hyphae in embryo sac. x 103 diam. 



Plate XXI. 

 Figures 1-6 show^ detail of ovule illustrated in Plate XX. (Stage A). 



Fig. 1. — Three cells of nucellus, showing the intra-cellular iiature 

 of the fungus. These cells react to the violet stain, the 

 rest of the nucellus staining with bismarck brown. 



(n) nucleus; (h) hyphae; (h^) fine ramifications of 

 hyphae in the cells, x 1100 diam. 



Fig. 2. — A cell from the carpel wall which is being attacked by the 

 fungus and used ais food-material for the fungal system, 

 (h) hyphae running between the cells; (h^) fine pene- 

 trating threads; (g) starch grains being digested by 

 hyphae; (s) septum in hyphae. x 1100 diam. 



Fig. 3. — ** Knots " formed by the hyphae wrapping round the 

 cells as a preliminary to their entrance into them. The 

 lightly-shaded portions are lying at a lower level than 

 the darker sections of the hyphae. x 1100 diam. 



Fig. 4. — A vascular element from the stalk end of the carpel 

 wall, showing the close association of the fungus. 



(r) thickenings on vessel; (h) hyphae. x 1100 diam. 



Fig. 5. — Cells from the distal end of the carpel wall. 



(g) starch groups; (h) large intra-cellular hyphae; 

 (hi) fine hyphal threads completely wrapping round 

 grains prior to digesting them, x 1100 diam. 



Fig. 6. — Ovum and synergidae; showing presence of hyphae in 

 ovum before any divisions have occurred in it. 



(o) ovum; (s) synergidae; (n) nucleus (nuc) nucellus; 

 (h) hyphae. x 700 diam. 



