14 BTJLI.ETIjSr 951, U. S. DEPARTMENT OF AGRICULTURE. 



The value of a continuous-temperature record in the process of 

 incubating cultures is great. Such records are not only of value in 

 showing the temperature at all times throughout the period of incu- 

 bation, but' they may be dated and filed for reference, thus making 

 it possible to determine with accuracy the temperature maintained in 

 the incubating process on any previous date. 



Fig. 11. — Chart showing the temperature maintained in the incubating room of the 

 Pathological Division, January 22 to 29, 1918. Note that night temperatures especially 

 are practically without fluctuation. 



The chart in figure 11, taken from the incubator room equipped 

 with the temperature-control system designed in the bureau, shows 

 the temperature maintained for the week January 22 to 29, 1918 — 

 typical of the winter season. Attention is invited to the fact that 

 during the night periods, when the room is closed, there is scarcely 

 any variation in the temperature. During the day periods, however, 

 when the door is opened for storing or taking out specimens, tem- 

 perature variations occur. But in no instance do the variations 

 texceed 1° C, and they exist for only a few minutes at a time. Even 



