AGARICUS 455 



By applying the ordinary tests, it may be shown that the 

 incrustation consists of calcium oxalate. 



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 mycelium, and then the relation 

 of the latter to the young mushrooms may be clearly 

 seen. If a series of specimens illustrating the develop- 

 ment 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 

 longitudinally 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 hymenial lamellae). 



6. Note further the ring or annulus, which remains 

 persistent on the stipe of the mature mushroom, and 

 marks the line of rupture of the velum : the corre- 

 sponding, irregular fringe at the margin of the pileus 

 is also to be recognized. 



7. Removing the mature pileus, examine its lower 



