WATTERSON: EFFECT OF CHEMICAL IRRITATION 295 
and the water was twice distilled. The dishes and flasks in which 
the cultures were grown were rinsed with dilute HCl, carefully 
washed with double-distilled water and dried in a dry sterilizer. 
The spores were sown by rubbing small pieces of glass rod, 
exactly equal in size, upon the dry stock supply, and then trans- 
ferring them to the dishes by means of glass tipped forceps. It was 
found convenient to keep a supply of the concentrated nutrient 
solution on hand, containing all the ingredients except sugar. 
The necessary amount was diluted and the sugar added when the 
series was set up. 
At first the Godlewski apparatus used by Kunstmann was 
employed. This consisted, in brief, of a bell-jar enclosing two 
crystallizing dishes ; the smaller of these held the fungus growing 
on 75 c.c. of the nutrient solution, and rested upon a glass strip 
placed across the larger dish which contained 150 c.c. of a 10 per 
cent. solution of KOH. The mouth of the jar was closed with a 
rubber cork provided with two holes through one of which passed 
a thermometer, and through the other a glass tube leading to a 
mercury valve, with which, in turn, was connected a KOH tube 
in such a way that air could pass into the jar, but could not escape 
from it. The bell-jar was sealed to a ground glass plate by means 
of vaseline and the joining was then painted with two coats of 
shellac to make it water tight. Three jars were used, one to 
serve as a control, and two for the experiment ; the results given 
are, unless otherwise stated, the average of the two grown at the 
Same time and under the same conditions. The greatest difficulty 
Was experienced in keeping the cultures at an even temperature, 
approximately near the optimum for Sterigmatocystts, which is 
30-34° C. The plan finally followed was to place all three jars 
in a zinc trough partly filled with water, the temperature of which 
would change more slowly than that of the air, and then to 
enclose the whole in a wooden box placed near a steam radiator. 
Under these conditions the temperature was raised to the neigh- 
borhood of 30° C., and varied not more than three or four de- 
grees during any one experiment. 
At the close of the experiment the fungus was killed with 
formalin as soon as the jar was opened, washed with distilled 
water, collected in weighed filter papers, dried in an oven at a 
