274: 



ASCOMYC'ETES. 



glutinous ; it consists of small eight-spored asci over which 

 project septate paraphyses, and also non-septate paraphyse-like 

 structures which discharge a brown secretion. The ascospores are 

 unicellular, hyaline, and canoe-shaped ; on germination they give 

 off a germ-tube which immediately develops into a septate 

 mycelium. The mycelium is found in the intercellular spaces 

 of the rind-parenchyma, but in the bast it grows both inside the 

 cells and between them, so that the sieve-tubes are often completely 



Fig. U(i.— Ront-system of a Silver Fir 

 overgrown and killed by the mycelium of 

 Rliizina uiululala. (After Hartig.) 



Fig. 147. — Ascospores of Rhizina. a, As 

 taken from the ascus ; b, 24 hours after 

 sowing ; c, 48 hours after sowing ; d, the 

 spore of c enlarged. (After Hartig.) 



filled up. Masses of fungoid pseudoparenchyma are frequently 

 formed between the dead and diseased tissues. Strands of the 

 nature of Rhizoctonia emerge from the diseased roots, many 

 of them carrying thread-like processes, at the extremity of 

 which an oil-drop is secreted and escapes on rupture of the apex. 



According to Hartig very tiny conidia are abjointed from 

 the mycelium. 



De la Boulage^ and Prillieux have botli come to the conclusion 

 that "la maladie du rond " of Pinus sylvestris and P. maritima 

 is the same disease as the " ring-disease " caused by Bhizina. 

 ' Bull, de la soc. de-s Afjric. de France, 1880. 



