MISCELLANEOUS CBOPS. 147 



grorip of wMch tlie " smuts " are important members. 

 Fig. 49 represents a transverse section of a root with 

 nodule. In very thin sections under high power, the 

 nodules are seen to be filled with hyphae and spores. The 

 spores of this fungus are more or less v-shaped, and are 

 formed by division of the protoplasmic contents of the 

 hyphal filaments which ramify in the root-tissues of the 

 host>-plant. Unlike most of the members of the Ustila- 

 ginece, the hyphse of Ustilago cucumeris i are not divided 



aiui spores 

 •Xyleni, 



Epijijirmis 



Fig. 49. — Tbansvebse Section of a Boot with Nodule. 

 (Under low power.) 



by transverse septa. The hyphse (which are many times 

 thicker than the cell-walls of the adjacent tissues) pass, 

 cell by cell, through the cortex of the rootlet, and some- 

 times across the intercellular spaces (Mg. 50). Branching 

 of the hyphee is well marked in the tissues of the nodules, 

 and sometimes they send out lateral branches which end 

 abruptly in the cells. The protoplasm of the nodular cells 

 after a time becomes vacuolated (Fig. 50) and filled with 

 spores. The spores of the cucumber-root fungus are 

 found in the soils (where Cucumis sativa has been grow- 

 ing) in the autumn and early winter, having been liber- 



' Originally described as Ustilago cueumis. 



