5o6 
F. D. HEALD AND R. C. WALTON 
Expulsion was light but all the specimens shot more or less. The 
control specimens at laboratory temperature, 70.8° F., gave an 
abundant spore expulsion. 
{d) Temperature 5Q°-65.5° F. Average 62.5° F. The specimens 
were collected at Emilie, Bucks County, Pa., Feb. 6, 1913, and pre- 
pared by the usual method. From the time of collection until Febru- 
ary 13 the specimens were kept moist. The bark was wet and the 
test started on this dace but the trays were kept for two days at 
laboratory temperature to make certain that the material was in the 
proper stage of development for expulsion. On February 15,1913, two 
trays were put in the cold room and two kept in the laboratory for a 
control. 12 specimens were used for the experiment proper, and 12 
for the control. The test specimens were kept in the cold room at an 
average temperature of 62.5° F. for 17 days, during which time expul- 
sion was light. All of the specimens showed some active ostioles. 
The control specimens shot abundantly. At the end of the 17 days, 
on March 4, 191 3, the two cold room trays were put in a room held at 
a temperature of 24° F. for one week. The bark was of course frozen 
solid during this time. At the expiration of the week, they were again 
removed to the first cold room and observed for 19 days, or until March 
31. The first day after removal from the 24° F. cold room into the 
61.5° F. room all but four of the specimens showed expulsion, the 
highest number of spots for one slide being 52. On the second and 
third days there were no active ostioles and on the remaining 16 days 
very few in comparison with the first test of 17 days before being put 
in the room at 24° F. 
{e) Laboratory temperature, average 7i.g° F. All of the controls 
for the preceding and following experiments were run at laboratory 
temperature which averaged close to 72° F. At this temperature, 
as well as anywhere between 68° and 80° F., expulsion seems to occur 
very abundantly, whenever the proper moisture conditions are sup- 
plied. There does not appear to be any definite temperature which 
might be called the optimum or even any sharply defined limits. A 
few degrees one way or the other do not seem to make any appreciable 
difference. However, between the above stated temperatures, expul- 
sion appears to take place most freely (see Table II). 
(/) Temperature 6. 5° -8 0.5° F. Average 7p° F. The specimens 
were collected at Emilie, Pa., Nov. 5, 191 3. The same methods were 
used as described above except that a Prairie State chicken incubator 
