4 BULLETIN &88, XL S. DEPT. OF AGRICULTURE. 



0° C. In locations where the outer temperatures fall much below this 

 the bees are still able to maintain high temperatures, more bees taking 

 part in heat production. That such high temperatures can be main- 

 tained in these circumstances indicates that the shell of bees is effec- 

 tive as a heat insulator, but there is obviously a serious drain on the 

 vital capacity of the bees employed in producing heat. This is shown 

 by the rapid slowing down of the fanning of the wings as it con- 

 tinues. 



OUTLINE OF THE EXPERIMENT. 



To obtain information regarding the actual amount of work done 

 by a colony of bees while in the winter cluster, a small colony on 

 four combs having natural honey stores was placed in the chamber of 

 a small respiration calorimeter and their carbon-dioxid production 

 and oxygen consumption were measured for 10 days, while the tem- 

 perature of the air surrounding the bees was kept just low enough 

 so that the bees at all times would remain clustered. Throughout 

 the experiment the temperature of the air surrounding the bees and 

 at several points within the cluster was taken in order that this 

 work might be made comparable with the work on the behavior of 

 bees in winter as indicated by temperature responses. The bees were 

 located in a box within the calorimeter so constructed that while they 

 could not escape from it there was opportunity for abundant ventila- 

 tion. There were 14 thermocouples distributed in the hive in the 

 calorimeter in such manner that the temperatures in different places 

 inside and outside the cluster could be ascertained, the leads from 

 the thermocouples being extended through the outlet in the wall of 

 the chamber to a potentiometer on the outside. The temperatures 

 were read every half hour, day and night, for nearly 12 days. 



The thermocouples were so placed in the hive as to make it im- 

 possible for the clustered bees ever to occupy space in which some 

 of the thermocouples were not located, thus insuring that the 

 temperatures of the cluster might be obtained wherever the cluster 

 might move in the hive. The temperatures of all parts of the 

 hive outside the cluster could also be obtained by the arrangement 

 of these thermocouples. One of the thermocouples (No. 15) was 

 located outside the hive and 2 inches from it, thus giving the 

 temperature of the air of the chamber at this point. The readings 

 obtained with this thermometer are plotted in the charts on pages 15 

 to 18. A resistance thermometer was also placed in the chamber, but 

 at some distance from the thermocouple. Measurements made with 

 this thermometer are shown in the table on page 8. The two 

 records did not always exactly agree because the thermometers 

 were not together. 



