HEAT PRODUCTION OF HONEYBEES IN WINTER. 11 



There was no apparent effect on the activity of the bees from 

 variations in the carbon- dioxid content of the air in the hive, at 

 least within very wide limits. One column in the table shows the 

 percentage of carbon dioxid in the air at the time the residual analy- 

 sis was made each day. These figures tell little of the condition of 

 the air at any other period during the day ; they merely show what 

 it was after the air of the chamber had been passing through the 

 soda lime for at least an hour ; but unless the bees had been actually 

 more active at the time the residual analysis was made (which, 

 according to the thermocouples, did not occur in any instance) there 

 must have been at least as much and probably more carbon dioxid in 

 the air previous to the time of the analysis than is indicated by these 

 figures. It would appear, then, that throughout the whole of the 

 experiment the carbon-dioxid content of the air in the hive was 

 appreciably greater than that of normal air, which is probably the 

 usual condition in a hive; also there were outside variations in the 

 proportion of this gas in the air, as shown by the data in the table. 

 On December 21 and 22 arrangements were made to insure a consider- 

 able excess of carbon dioxid in the air. During most of the time on 

 these days the soda lime was removed from the train for purifying 

 the circulating air and the carbon dioxid was allowed to accumulate 

 within the respiration chamber while the water vapor was removed. 

 Starting with the content of nearly one-quarter of 1 per cent on the 

 20th, or almost eight times that in normal air, the increase continued 

 until in the whole air system of the apparatus, which was about 170 

 liters, there was included over 10 liters of carbon dioxid before the 

 period ended on December 21, a proportion more than 200 times that 

 in normal air. There is no significant change in the curves on page 18 

 showing the behavior of the bees, to indicate that they were materially 

 affected by these abnormal conditions. The curve for thermocouple 

 !N o. 7 continued at the same level for nearly 12 hours, then began to 

 rise slowly ; those for Nos. 12 and 6 fell somewhat for about 12 hours 

 and then maintained a level for the remainder of the period. There 

 would appear to be on the whole a quieting of the bees for this day, 

 but this could be hardly attributed to the quantity of C0 2 present, 

 for on the following day, when there was a still greater concentration, 

 the activity of the bees increased. 



From the character of the curves in these two days it would be 

 expected that the carbon-dioxid production on the 22d would exceed 

 that of the 21st, but not necessarily by nearly 50 per cent as shown 

 in the values in the table. It is not unlikely that some of the carbon 

 dioxid measured on the 22d was produced on the 21st. Uninten- 

 tionally, replacement of the soda lime in the air circulating system 

 was delayed until one hour before the close of the first period, and 



