PERFECT SOCIETIES OF INSECTS. 199 
which often are suspended from the hives in summer, 
when they are incommoded by the heat of the sun, fan 
themselves: with great energy. But if by any means a 
shadow is cast over any portion of the group, the venti- 
lation ceases there, while it continues in the part which 
feels the heat of the sun. The same cause produces a 
similar effect upon humble-bees, wasps, and hornets. 
Amongst the bees, however, it is remarkable that ven- 
tilation goes on even in the depth of winter, when it can- 
not be occasioned by excess of heat.—This therefore can 
only be regarded as a secondary cause of the phenome- 
non. [rom other experiments, which, having already 
detained you too long, I shall not here detail, it appears 
that penetrating and disagreeable odours produce the 
same effect?. Perhaps, though Huber does not say this, 
the odour produced by the congregated myriads of the 
hive may be amongst the principal motives that impel 
its inhabitants to this necessary action. 
Whatever be the proximate cause, it is I trust now 
evident to you, that the Author of nature, having as- 
signed to these insects a habitation into which the air 
cannot easily penetrate, has gifted them with the means 
of preventing the fatal effects which would result from 
corrupted air. An indirect effect of ventilation is the ele- 
vated temperature which these animals maintain, without 
any effort, in their hive :—but upon this I shall enlarge 
hereafter. 
Bees are extremely neat in their persons and _habita- 
tions, and remove all .nuisances with great assiduity, at 
least as far as their powers enable them. Sometimes 
4 Yuber, 1. 353— 
