r cauliflower,
lettuces, snap beans, and other crops. But as the mushroom growers who
restrict themselves entirely to mushrooms, and who, after the mushroom
beds have finished bearing, have no further use for the manure in the
spent beds, are always able to dispose of it at one-half the cost price.
It is excellent for garden crops and as a topdressing for lawns, on
account of its fineness and freedom from all rubbish as sticks, stones,
old bottles, old shoes, and the like, is in much demand.

CHAPTER XXI.

MUSHROOM GROWING IN THE PARIS CAVES.

In caves and subterranean passages underneath the city of Paris and its
environs, thousands of tons of mushrooms are artificially produced every
year. These underground caves and tunnels are abandoned quarries from
which white building stone and plaster have been excavated, and as the
veins of stone permeated through the bowels of the earth, 40 to 125 feet
deep, so were they quarried, and the blocks brought to the surface
through vertical shafts. It is these tunnels, varying in height and
width as the veins of stone varied, that are now used for
mushroom-growing. M. Lachaume, in his book, _The Cave Mushroom_, tells
us: "In the Department of the Seine there are 3000 quarries; those which
have been abandoned and which are situated close to Paris at Montrouge,
Bagneux, Vaugirard, Mery, Chatillon, Vitry, Honilles, and St. Denis, are
used by the 250 mushroom-growers of the Department. There are several of
these quarries with horizontal galleries driven into the calcareous rock
from the level of the road, which are mostly large enough to accommodate
a good sized cart, but the majority can only be entered, like many coal
mines, by vertical shafts 100 to 125 feet deep, down which everything
has to pass. The laborers climb up and down a ladder, and the fresh
manure is shoveled down the shaft from above, the waste stuff and
mushrooms being hauled up in baskets from beneath by means of a
windlass."

The manure used is obtained from the Paris stables and furnished by
contractors, with whom the mushroom growers make special bargains
because they are very particular about the kind and quality of the
manure they use. Some of these growers use as much as 2000 to 3500 tons
of manure each a year for their mushroom beds. To the caves in the
immediate neighborhood of Paris the manure is hauled out in carts, but
to Mery and other places too far distant to be within easy carting
distance i