VENTILATION. 89 



ing, an equal current will force its way into the other, and 

 the lamp will bum until the oil is exhausted. 



It is on this principle of maintaining a double current 

 by artificial means, that bees ventilate their crowded 

 habitations. A file of ventilating bees stands inside and 

 outside of the hive, each with head turned to its entrance, 

 and while, by the rapid fanning of their " many twinkling" 

 wings, a brisk current of air is blown out of the hive, an 

 equal current is drawn in. As this important office de- 

 mands unusual physical exertion, the exhausted laborers 

 are, from time to tune, relieved by fresh detachments. If 

 the interior of the hive permits inspection, many ventila- 

 tors will be found scattered through it, in very hot weath- 

 er, all busily engaged in their laborious employment. If 

 its entrance is contracted, speedy accessions will be made 

 to their numbers, both inside and outside of the hive; and 

 if it is closed entirely, the heat and impurity quickly in- 

 creasing, the whole colony will attempt to renew the air 

 by rapidly vibrating their wings, and in a short time, if 

 unrelieved, will die of suffocation. 



Careful experiments show that pure air is necessary 

 not only for the respiration of the mature bees, but for 

 hatching the eggs, and developing the larvae ; a fine net- 

 ting of air-vessels enveloping the eggs, and the cells of the 

 larvae being closed with a covering filled with air-holes. 



In Winter, if bees are kept in a dark .place, which is 

 neither too warm nor too cold, they are almost dormant, 

 and require very little air ; but even under such circum- 

 stances, they cannot live entirely without it ; and if they 

 are excited by atmospheric changes, or in any way dis- 

 turbed, a loud humming may be heard in the interior of 

 their hives, and they need almost as much air as in warm 

 weather. . 



If bees are greatly disturbed, it will be unsafe, espe- 



