266 FOUNDATIONS OF BOTANY 
fruiting cells (basidia) which project at right angles to the gill and 
bear the spores. At how many points (sterigmata) on each basidium 
are spores attached? Draw a basidium, preferably one from which 
the spores have not yet fallen. 
THE STUDY OF YEAST (SACCHAROMYCES CEREVISIZ) 
320. Growth of Yeast in Dilute Syrup. — Mix about an eighth of 
a cake of compressed yeast with about a teaspoonful of water and 
stir until a smooth, thin mixture is formed. Add this to about half 
a pint of water in which a table- 
spoonful of molasses has been 
dissolved. Place this mixture in 
a wide-mouthed bottle which holds 
one or one and a half pints, stop- 
per very loosely! and set aside for 
from twelve to twenty-four hours 
in a place in which the temper- 
C ature will be from 70 to 90 degrees. 
Watch the liquid meantime and 
note : 
(a) The rise of bubbles of gas 
in the liquid. 
(b) The increasing muddiness 
of the liquid, a considerable sedi- 
ment usually collecting at the end 
Fic. 196. — Part of the Preceding Figure. of the time mentioned. 
(x about 300.) (c) The effect of cooling off the 
C, layer of cells immediately under the contents of the bottle by immers- 
hymenium ; 8, s', 8’, three successive ing it in broken ice if conveniem™ 
stages in growth of spores. : capa 
or, if this is not practicable, by 
standing it for half an hour in a pail of the coldest water obtainable, 
or leaving it for an hour in a refrigerator, afterwards warming the 
liquid again. 
(d) The effect of shutting out light from the contents of the 
bottle by covering it with a tight box or large tin can. 
1 If the cork is crowded into the neck with any considerable force, pressure 
of gas and an explosion may result. 
