290 STRUCTURE AND LIFE HISTORIES 



280. Mushroom Culture. — The growing of mushrooms 

 for the market is a very important industry, especially 

 in some localities. Cultures are usually started from 

 "spawn," obtained from the seedsman in the form of 

 "bricks." These bricks consist largely of mycelium, 

 tightly pressed together. When the bricks are broken 

 up and distributed through a "bed" of soil and manure, 

 properly prepared, the mycelium resumes its growth, and 

 soon begins to produce the "buttons" (Fig. 204), which 

 finally develop into mature mushrooms. 



The industry is commonly carried on in cellars and 

 caves. This is not necessary, for the meadow-mushroom, 

 as its name clearly implies, grows in nature in open 

 meadows and pastures. But, since the fungi have no 

 chlorophyll, they do not need the light, and so space 

 can be used for their culture that would not well serve 

 any other useful purpose. 



FUNGI THAT CAUSE PLANT DISEASES 



281. Govemment Regulation. — Fungi that grow as 

 parasites on green plants cause serious disturbances of 

 the normal Ufe-processes and structure of their hosts, 

 interfering with healthy growth, and causing plant 

 diseases. Since the fungi are reproduced by spores, these 

 diseases may rapidly spread by contagion. On this 

 account state legislatures and the national Congress have 

 been obliged to pass stringent laws governing international 

 and interstate traffic in plants liable to disease, providing 

 for their careful inspection and quarantine. The United 

 States Government maintains an expert pathologist 

 continuously at the port of New York to inspect plants 



