Plate 10. 



Mushrooms begin their lives in the laboratory, where trained scientists select the choicest 

 mushrooms and place sections in sterile glass tubes. These tubes, plugged with cotton, are 

 placed in an incubator and held at constant temperature and humidity for 72 hours. During 

 this lime spores drop from the gills of the mushroom and produce a spore print within the 

 glass tube. 



Plate 11. 

 Jars of nutrient medium for the pure culture of mushroom spawn 

 are sterilized in large steam retorts. 



