CONTROL OF INCUBATING TEMPERATURES IN LABORATORIES. 15 
tl^ese temperature variations may be materially lessened if the door 
is quickly opened and closed and kept closed while storing or remov- 
ing specimens. A similar chart, figure 12, covering the week August 
G to 13, 1918, shows the results obtained during a typical summer 
period. The incubator room Avas entered only about twice during 
this week; consequently the temperature was maintained practically 
constant throughout the period. 
Fig. 12. — Chart showing temperatures maintained in incubating room of Pathological 
Division, August 6 to 13, 1918. Note that variations are exceedingly small. 
The chart in figure 13 was. taken in one of the incubator rooms 
equipped with a control system made up largely of assembled com- 
mercial apparatus. The curve shows that while the average tem- 
perature was about that for which the control was adjusted it was 
not so uniform as the temperatures shown in the previous charts. 
IVhile this latter temperature-control system is not so sensitive or 
reliable as the former, and hence requires closer attention and more 
frequent adjustments, it has the advantage of being assembled from 
commercial apparatus. 
