Dorothy M. Cayley 463 



On the other hand, in the case of the Rusts in the Gramineae, 

 although Beauverie(2) observed sori of uredospores, teleutospores, and 

 myceUum in the parenchymatous tissue of the caryopsis near the 

 furrow, and in the pericarp beyond the region of the furrow, the 

 myceUum could not penetrate the layer of strongly cuticularised tissue 

 immediately outside the aleurone layer of the seed itself, unless this 

 protective layer had been ruptured from some cause or other, in 

 which case, bacteria were generally found to be present. 



The most marked instance oi a symbiotic bacterium inside the seed 

 is that of Ardisia crispa and A. crispa var. comjxicin (Miehe(ii)). 

 The bacteria occur in the plant m nodules or pockets at regular 

 intervals 30 — 50 mm. apart at a short distance from the edge of the 

 leaf, in the buds and inside the seed between the embryo and the 

 endosperm. Miehe considers this a case of strict symbiosis. 



Instances of seed-coat parasitic infection and infection of the 

 ovarial tissues are not uncommon. In the mycorhiza-bearing plants 

 the mycelium of the symbiotic fungus in the Ericaceae was also found 

 to be present in the seed-coat, but not in the internal tissues of the 

 seed (Rayner(i3)). 



Symptoms of the Disease. 



The general symptoms are as follows : in mild cases, after germina- 

 tion, the shoot can develop normally, but in bad cases it is frequently 

 abortive, brown, and dead at the tip, and laterals grow out prematurely 

 to take the place of the main shoot (Plate V, fig. 1). Quite early in the 

 development of the plant, when the plumule is from half an inch and 

 upwards in length, light brown longitudinal streaks can sometimes be 

 seen on the stem and root. In very bad cases little or no germination 

 takes place. After this stage no further definite signs are noticeable 

 till about the flowering period. Then the development of the disease 

 depends a good deal on the external conditions. If the weather is 

 warm and dry, and the plants are growing vigorously, the disease 

 develops rapidly, and in a few days the plants may become unhealthy 

 and change colour. The stem turns slightly brown and looks somewhat 

 water-soaked. Brown longitudinal streaks appear at the base of the 

 petioles on either side of the stem which is continuous with the midrib 

 of the leaf. The streaks sometimes spHt open and dry out. The collar 

 may be badly disorganised. The leaves become spotted and yellowish 

 in colour, with darkened veins. Sometimes the surface of the pod is 

 roughened or embossed. This is caused by the enlargement of cortical 



