ARMILLARIA MELLEA 89 



wild Mountain Ash {Pyrus Aucuparia) upon the base of the trunk of 

 which a number of fruit-bodies of the Honey Fungus appeared. 

 In 1902 a still larger number of fruit-bodies came to maturity upon 

 the tree, and the photograph which is here reproduced was then 

 taken (Fig. 38 ; cf. also Fig. 30, Vol. I, p. 78). A small piece of the 

 bark was removed and was found to be phosphorescent in the 

 dark. The next year only a few fruit-bodies developed, and there- 

 after no more at all. The tree in 1921, i.e. after a lapse of twenty 

 years, was still flourishing. It thus appears that the mycelium of 

 the fungus, after succeeding in entering the tree, spreading beneath 

 the bark, and maintaining its vitality for at least three years, died 

 and left its host-plant victorious in the struggle. One might 

 have expected that the parasite would complete the destruction 

 of its victim. The reason for this failure I am not able to 

 suggest. 



Armillaria mellea can be grown in pure cultures without difficulty. 

 Brefeldi (1877) germinated spores in a drop of plum decoction on a 

 glass slide and then transferred the resulting mycelium to a large 

 mass of plum decoction contained in a crystallising dish. He soon 

 obtained numerous rhizomorphs but did not succeed in raising any 

 fruit-bodies. Molisch 2 (1904), using a Petri dish, sowed spores in 

 a plum decoction solidified with agar and then transferred the 

 mycelium to plum decoction or wet bread-mash contained in an 

 Erlenmeyer flask. Like Brefeld, he soon obtained rhizomorphs, 

 but, on the bread-mash, at the end of two months from sowing the 

 spores, he also obtained several fruit-bodies. Both Brefeld and 

 Molisch observed that the mycelium in their cultures was splendidly 

 luminescent. 



Hans Kjiiep ^ obtained separate mycelia each of which originated 

 from a single spore ; and, after 2-4 weeks, he found that, although 

 the cultures exhibited no trace of fruit-bodies, yet the aerial hyphae 

 had given rise directly to basidia bearing basidiospores. This pro- 

 duction of scattered basidia on a mycelium of monosporous origin 



1 0. Brefeld, Untersuchungen, Heft III, Leipzig, 1877, pp. 141-146. 



2 H. Molisch, Leuchtende Pflanzen, Jena, 1904, pp. 36-38. 



3 H. Kniep, " tJber das Auftreten von Basidien im einkernigen Mycel von 

 Armillaria mellea,'' Zeitschrift fiir Botanik, Jahrg. Ill, 1911, pp. 529-553. 



