1916] 



DUGGAR RHIZOCTONIA CROCORUM AND R. SOLANI 



415 



toplasm is dense towards the tips of branches and vacuolated 

 farther away. The hyphae are somewhat flexuous, branched 

 (sometimes closely), with the branches arising at right angles 

 to the main hypha, and with a partition wall laid down at 



.1). With age the hyphae become 



the branching is 



to 



not over 10 n distant 

 rigid, someAvhat less in diameter, 4-8 n 

 distant, and these branches readily break off at the first par- 

 tition wall 



to" 



2). At the point of union the diameter is 

 uniform with the main hypha. The partition walls are distant, 



Fig. 2. Rhizoctonia Crocorum: Mature root-investing hyphae. 



often 120-200 n apart. The walls now possess the violet- 

 brown pigment and in the lumen little or no protoplasm is 



observable. 

 The internal mycelium is likewise branched, septate, often 



ssociated 



loose strands 



between the cells or 



g them 



In the early stages of the disease, so far 

 as reported, these internal hyphae are nearly colorless ; Prunet 

 reports that there are sometimes areas of brown mycelium in 

 the attacked tissues, and this I find particularly true of 

 asparagus. The internal hyphae are generally of less diam- 

 eter than those constituting the external mat. 



Disregarding for the time the small cushions already men- 



