2QO 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. Government Regulation. Fungi that grow as 
parasites on green plants cause serious disturbances of 
the normal life-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 
