150 ARM ILL ARIA MELLEA, 



horizontally for a short distance and then di'opped by their 

 own weight between the gills. For this purpose it is neces- 

 sary that the gills should be vertical, and this orientation 

 is secured by a tri])le action (Buller, 1909). The stipe is 

 vertical, the pileus adjusts itself to a horizontal position, 

 and finally the gills place themselves vertically. 



A section of the gills stained with iodine disclose some 

 interesting facts with regard to the distribution of glycogen, 



the principal reserve carbohydrate of the 

 fungus. In young basidia glycogen is 

 fairly generally distributed ; but, as they 

 get older, part of the glycogen is passed 

 into the spores, and the rest is left as a 

 di'op at the upper end of the basidium. 



Fig. 62. Hvmenial Basidia which have lost all their spores 



layer of Armillana gtill contain this drop of glycogen, and 



its function is probably to provide the 

 osmotic pressure necessary for the discharge of the spores 

 (see p. 104). The ripe spores measure about 9X6/^, and are 

 somewhat reniform. 



Rhizomorphs. Armillana mellea has a more specialized 

 vegetative S3'stem than any other known fungus. In 

 a nutiient medium such as a rotten stump, and especially 

 in the space between the wood and the bark of dead trees, 

 it makes a reticulated mass of somewhat thick strands or 

 ihizomorphs, each flattened thread of which resembles 

 a black leather boot-lace (figs. 63 and 64). From points 

 beneath the soil these rhizomorphs send out branches into 

 the earth, which are of a somewhat different type, being 

 round in section instead of flat, and having fewer branches. 

 Both types of rliizomorphs were known long before they 

 were associated with any particular fructifications, and 

 they long went by the name Rhizomorpha subcordcalis and 

 Rh. aubterranea} Persoon, respectively. It was not even 

 determined that the two forms belonged to the same species 



^ Sowerby, vol. iii, 180.3, figures live 8j)ecie8 of Rhizo>nor})ha, two of 

 which arc ccTtainly Hh. finhttrranca. The othcr.s are doul)lful, but none 

 reacmbk'S iih. subcorlicalis. 



