242 



DEVELOPMENT OF A MUSHROOM 



The Mushroom or Toadstool. — The common umbrella type of 

 mushroom consists of a stalk or stipe and a cap or pileus, on 

 the underside of which are located radiating plates or gills (Fig. 

 167, A). This structure originates on a strand of the mycelium 

 as a very small ball composed of a mass of interwoven hyphae 



Fig. 167. Habit of a poisonous mushroom, Amanita: A, the mature 

 mushroom — s, stipe; p, pileus; g, gills; a, annulus; v, volva, a part of which 

 appears in patches on the top of the pileus. C, young form of the Amanita, 

 the volva beginning to break. D, later development, the volva completely 

 ruptured, disclosing the pileus, stipe and velum, vl. — H. O. Hanson. 



(Fig. 166, 3). Soon, however, the hyphae of this mass begin 

 to grow in a very regular manner. At first the growth results 

 in the formation of a cavity in the upper part of the ball that 



