192 



PENICILLIUM AND AGARICUS 



LESS. 



of the distance from the circumference of the pileus to the 

 stalk. In the common edible mushroom (Agaricus cam- 

 pestris) these lamellae are pink in young specimens, and 

 afterwards become dark brown. 



FIG. 41. Agaricus campestris. 



A, Diagrammatic vertical section, showing the stalk (sf) springing 

 from a mycelium (my} y and expanding into the pileus (p), on the under 

 side of which are the radiating lamellae (/). 



B, transverse vertical section of a lamella, showing the hyphce (hy) 

 turning outwards to form the layer of club-shaped cells (a) from which 

 the sterigmata spring. 



c, one of the club-shaped cells (a\ highly magnified, showing its two 

 sterigmata (stg), each bearing a spore (sp). 

 (B and c after Sachs.) 



The mushroom is too tough to be readily teased out like 

 the mycelium of Penicillium, and its structure is best in- 



