24 



DIVISION I.— GENERAL MORPHOLOGY. 



end. Agaricus melleus is chiefly a parasite on living European Abietineae (see 

 Division III). It makes its way into the roots or the base of the stem beneath the 

 ground, and the mycelium spreads in the cambium zone and in the young bast, forming 



FIG. 9. Agaricus melleus. Me. 

 dian longitudinal section through 

 the growing apex of a subterra- 

 nean mycelial strand, seen by trans- 

 mitted light. Magn. 40 times. 



Fig. 10. Agaricus melleus. Thin median longitudinal section through the extremity 

 of the growing apex of a subterranean mycelial strand. Magn. 250 times, but the drawing 

 completed under higher magnifying power. 



compressed or membrane- like expanded networks of strands at the cost of the sap- 

 containing layers of tissue, and also sends out a large number of single hyphae from 



these strands into the rind and wood, and 

 especially into the medullary rays, where 

 they spread widely. From these intra- 

 malrical, especially subcortical, parts other 

 strands may proceed which develope as 

 ex I ram a trica I strands usually in the soil, 

 and are therefore subterranean, and branch 

 and spread the Fungus over wide distances 

 from one tree to another. These strands 

 become more than 3 mm. thick and are 

 round on the transverse section ; they can 

 also develope into enormous masses in 

 moist rotting timber. 



The cylindrical subterranean strands 

 consist when fully formed of a dark-brown, 

 brittle, usually smooth peripheral tissue or 

 rind enclosing a white finely-felted me- 

 dulla. The rind, which in stout specimens 

 has the thickness of paper, is formed in 

 its outer portion of about twelve or more layers of cell-rows (hyphae) running down the 

 length of the strand, and connected with one another laterally without interspaces. 



Fig. 11. Agaricus melleus. Transverse section through a 

 young branch of a subterranean I it the 



lower half of Fig. 9. a the axile lar>' 

 the outside into the later-formed rind. 1 



rind is at b ; outside b is the cow I with 



numerous spreading hair-like branches h. Magn. 190 times. 



