228 ELEMENTS OF BOTANY 
ciuster-cups, note whether they are any more abundant on this bush 
than on others. Are you sure that the rust you have is the one 
to which the barberry cluster-cups 
belong? 
THE STUDY OF PSALLIOTA 
292. Occurrence.— The common 
mushroom, Psalliota or Agaricus cam- 
pestis, grows in open fields in the 
United States and Europe. It is the 
mushroom most extensively culti- 
vated for market, and if not found 
in the field it may be raised from 
“spawn” (mycelium), put up in the 
shape of bricks, and sold by seeds- 
men in the large cities. Those who 
make a specialty of selling it furnish 
directions for culture free. .A moder- 
ately warm cellar or basement makes 
an excellent winter garden for mush- 
rooms. 
293. Structure of Mycelium. — 
Examine some of the spawn, or 
mycelium, with the magnifying glass 
and the low power of the microscope, 
and with a power of 200 diameters 
or more examine the individual 
hyphe which compose it. Are the 
Fie. 163. A Mushroom 
‘eke hyphz united in cord-like strands or 
Armillaria mellea). ‘i . : 
( elles) otherwise, or are they entirely sepa- 
my, mycelium; e¢, ¢%, &”, young 3 wae . 
Y, mycetums & Cy, young yate? Look for cross-partitions in 
buttons’’; sf, stipe or stalk; We fare, Me Z ‘ 
r, ting; g, gills. the hyphe. Is there any peculiar 
structure to be found at these places ? 
Are the cross-partitions near together or widely separated ? 
294. The Spore-Plant.— Search for indications of fruiting, and 
note the appearance of the “button mushrooms” in all available 
stages. Draw. See if at any stage up to maturity an outer envelope 
