Jan. 23, 1917 
Temperature Relations of Apple-Rot Fungi 
141 
this produced but very small colonies. At a temperature of 3 0 to 4 0 
Monilia fructigena made a scant development, and at 9 0 to io° all of the 
fungi made some growth, the species of Monilia and Penicillium both 
fruiting within 11 days. 
EXPERIMENTAL INVESTIGATIONS 
APPARATUS 
The experiments reported in this paper were carried out in refrigerator 
boxes constructed especially for the work. The low temperatures were 
obtained by means of a sulphur-dioxid refrigerating machine. This 
machine was stopped and started automatically by means of a tumbler 
switch and a 3-step starter and the brine thus kept within a range of 2 0 C. 
In the cooler months it was kept at a temperature of — 8° to — 6°, but in 
the warmer months it was necessary to carry it one or two degrees colder 
in order to obtain the required refrigeration. In testing out regulators 
it was found that a short bimetallic form was entirely unsatisfactory in 
humid weather, as the moisture condensed on the cold metal at the con¬ 
tact points and caused considerable trouble in the operation of the 
machine. Later, a regulator was used in which the points of contact 
were placed a long distance from the brine and the make-and-break 
brought about by means of a column of mercury under pressure; this 
was found entirely satisfactory. The brine was circulated through the 
pipes in the boxes by means of a rotary pump which was kept in operation 
all the time. Different amounts of brine were thrown into the different 
boxes by means of control valves on the pipes at the entrance to the 
boxes, thus making it possible to maintain a different temperature in 
each box. 
The walls of the boxes were 5^ inches thick, sheet cork and heavy 
paper being used as insulating material. A galvanized-iron box was 
placed inside the wooden box. On the sides and bottom there was a 
3-inch air space between this inner metal box and the outer box, while 
at the top there was a space of less than an inch between the metal box 
and the brine pipes. The inner box was 2 feet high and approximately 
3 feet square. The air was circulated in each double box by means of 
blower fans that were operated constantly, one fanning the air over 
the brine pipes and through the air space between the two boxes, and the 
other stirring the air of the inside box. The air from this latter fan was 
carried across the top of the box by means of a special duct and dis¬ 
charged on the opposite side, thus insuring a complete circulation. A 
closely fitting slide door in the metal box made it possible to circulate 
the air from over the brine pipes directly through the inner box if quick 
cooling was desired. The temperature of the air space between the 
boxes was always kept a few degrees lower than that desired in the inner 
box, and the latter brought to the required temperature by the use of 
electric lamps. Since the brine was kept at a practically constant tern- 
