New York Agricultural Experimbt>}t Station. 101 



to be devoid of protoplasm, and from neighboring protoplasmic 

 cells the germ tubes seem to pass into such empty cells as read- 

 ily as directly into the nutrient solution. When the germ tube 

 is from 10 ,« to 20 /x in length, it is invariably narrowed towards 

 the outlet from the parent cell, and a septum forms at a short 

 distance from this outlet, as in Fig. 4. Large, irregular, sclero- 

 tial bodies are sometimes found upon the beet, but they are by 

 no means of constant occurrence. 



If a part of a diseased beet is placed in a moist chamber, a 

 loose mycelial growth soon appears, and the threads may grow 

 out to the extent of half an inch or so. From this it is an easy 

 matter to obtain a pure culture by transferring some of this 

 mycelium to acidulated agar in petri dishes. The fungus grows 

 readily upon acidulated agar, while bacteria are for the most 

 part excluded. The fungus may then be transferred to bean pods, 

 or beet plugs, in test tubes, upon both of which media most 

 forms of Rhizoctonia seem to grow well. In pure culture a loose 

 mycelial growth first appeafs. This becomes brown in time. A 

 short tufted growth may appear later; and usually there is also 

 an effuse or crust-like sclerotial development. In culture the 

 sclerotia are usually irregular in form and brown in color. 



At this time it is not desired to enter into a discussion of the 

 slightly different morphological characters which may distinguish 

 the different forms of Rhizoctonia. 



BRIEF NOTES UPON RHIZOOTONIA IN BUROPB. 



{Historical.) 



The root-destroying fungus Rhizoctonia was first discovered 

 by De Candolle^ in 1815. He named two species: Rhizoctonia 

 medicaginis, occurring on Medicago, Trifolium and related hosts; 

 and R. crocorum, a fungus destructive to crocus bulbs. Of the 

 brief notes published upon other species of the fungus and other 

 host plants until 1851, a comprehensive summary is given by the 

 brothers Tulasne.^ They believed that the several species then 



' De CandoUe— Mem. d. Mus. d'hist. nat., 1815. 

 "Tulasne, L. et C— Fungi Hypogaei, pp. 188-195, 1851. 



