202 



BOTANY OF THE LIVING PLANT 



Externally no fungus is obvious, but if sections of the root be cut the third 

 to the fifth layers of the cortex have their cells crowded by coiled fungal 

 hyphae, which a.re enclosed in the still living nucleated protoplast. The infec- 



FIG. 153. 



Neottia nidus-avis. A = young tuber in section showing infected region shaded. 

 fi=rather older plant seen from outside. C = diagrammatic section of plant at 

 period of flowering, showing scale-leaves, axillary buds, and the insertion of the 

 prominent roots. The infected regions are shaded. >= rhizome seen from outside, 

 with roots removed: the scars (cs) show how numerous the roots are. (A, B, C 

 after Bernard ; D after Irmisch.) 



tion has been found to start with the germination of the seed, and is probably 

 not repeated (Fig. 154). Tufts of hairs, such as are present in Corallorhiza 

 and many other Orchids, are absent : but communication is kept up with the 

 soil by occasional hyphae which traverse the superficial cells. According to 



FIG. 154. 



Seed of Neottia infected by fungus, and showing the first stages of germination. 

 (After Bernard.) ( x 100.) 



age and position the fungal filaments show various stages of disorganisation. 

 In some cells only the indigestible remnants of the hyphae remain. The nuclei 

 of the digesting cells meanwhile increase in size, and starch appears in quantity 



