AGARICUS 227 



III. Remove a small piece of the mycelium, of an actively 

 growing culture, mount it in water, and having teased it out 

 carefully with needles, examine it in detail under a high power, 

 and observe 



1. The hyphse, of cylindrical form, and with rounded free ends. 



2. The irregular branching of the hyphae. 



3. The septa, which are transverse, and situated at irregular 

 intervals. 



4. Hyphae may frequently be seen to be incrusted by 

 numerous rod-like crystals. 



IV. Examine a portion of the mycelium which has begun to 

 produce " mushrooms " : with a little care the compost may be 

 entirely removed from considerable tracts of the branched my- 

 celium, and then the relation of the latter to the young mush- 

 rooms may be clearly seen. If a series of specimens illustrating 

 the development of the mushroom be examined with the naked 

 eye, the following observations may be made : 



1. That the mushrooms arise from the mycelium itself. 



2. That they appear first as irregular rounded, or oval, 

 upward growths, of denser texture than the mycelium itself. 



3. That on cutting one of the smaller mushrooms longi- 

 tudinally it appears to the naked eye to be of homogeneous 

 structure. 



4. That older mushrooms acquire an enlarged head (the 

 pileus), which is supported on a cylindrical stalk (the stipe). 

 In this state they are termed " button mushrooms." 



5. That as the pileus dilates horizontally, a rupture of a veil 

 of tissue (velum partiale) about its lower margin exposes a 

 complicated laminated structure formed internally (the gills, or 

 by menial lamellae). 



6. Note further the ring or annulus, which remains persis- 

 tent on the stipe of the mature mushroom, and marks the line 

 of rupture of the velum : the corresponding, irregular fringe at 

 the margin of the pileus is also to be recognized. 



7. Removing the mature pileus, examine its lower surface, 

 and note the radiating, more or less darkly coloured lamellae, 

 some of which extend the whole way from the margin to the 

 insertion of the stipe, others only a part of that distance. 



Q 2 



