296 WaATTERSON: EFFECT OF CHEMICAL IRRITATION 
temperature of 70° C., and after cooling in a dessicator was care- 
fully weighed. The KOH was diluted to 250 c.c.; the CO, was 
precipitated out of it by an equal quantity of barium hydrate, and 
the alkalinity of the remaining KOH was determined by titrating 
in the usual way with HCl of such strength that 1 c.c. of the 
acid = t mg. of CO,. The result was then subtracted from that 
obtained by treating a certain amount of the stock KOH in the 
same way, and thus the amount of CO, given off by the fungus 
was obtained. The results are given in milligrams both for the 
weight of the fungus and the amount of CO, given off. 
At the same time a series of experiments was carried on with a 
form of the Pfeffer-Pettenkofer respiration apparatus. The par- 
ticular object in using this was to determine the rate of respiration 
during short intervals of time. Certain practical difficulties made 
this impossible, however, at that time, and the attempt was 
abandoned. Later, the same apparatus was started again in a 
slightly different way ; 7. ¢., a strong solution of KOH was used 
and the same experiment was continued for a week at atime. It 
was set up in the dark room, which, being small and kept care- 
fully closed, could be maintained at a comparatively even tempera- 
ture in the neighborhood of 24° C. 
The air in entering the apparatus passed through three U-tubes 
filled with pumice stone wet with a strong solution of KOH which 
was frequently renewed. A Ba(OH), test-bottle was placed in 
the course to prove that no CO, passed over to the cultures, and 
the air was then distributed to these, four in number, by means of 
a T-tube and two Y-tubes. The cultures were grown in Erben- 
meyer flasks of about 250 c.c. capacity, in which only 75 c.c. of 
the nutrient solution was used. This brought the film of myce- 
lium at the level of the widest diameter of the flask and the flasks 
were all as nearly as possible of the same diameter. Between the 
culture flasks and the Pettenkofer tubes were interposed large 
test-tubes to prevent any possible backward flow of the KOH into 
the culture flasks; 150 c.c. of a 10 per cent. solution of KOH 
was introduced into the absorption tubes by means of a large 
pipette ; the stock solution was kept in a tightly stoppered bottle 
sealed with vaseline. At the exit end of the tubes were placed 
screw pinch-cocks to regulate the amount of air drawn through 
