520 
BEES AND BEE-KEEPING. 
the cluster during winter, to which I drew attention 
in 1879, have been remarkably corroborated by Pro- 
fessor N. McLain, who has detailed some experiments 
on this matter worthy of careful attention. His 
experiments were conducted in a cellar over the tem- 
perature of which he had full command. The bees 
entered the hybernating state when the external tem- 
perature was between 48° and 52°, the variation 
depending upon the amount of humidity present. 
At 41° Fahr. he found the shape of the cluster most 
permanent ; while that temperature was maintained, 
little change in the shape or location of the cluster 
could be seen, and functional activity seemed to have 
reached the minimum ; , even respiration appeared 
to be suspended,* and the outlines of the clusters 
remained unchanged for days together. Unrest and 
activity increased as the temperature neared the zero 
point. The degree of activity at 44° was not much 
greater than that at 41°. At intervals of about one 
week the bees roused themselves to activity, the form 
of the cluster changed, and, after three or four hours 
of cheerful and contented humming, having in the 
meantime appeased their hunger, the cluster reformed 
into a compact body, humming ceased, respiration 
became slow, and profound silence reigned in the 
hive. The more perfect the conditions, the longer 
the periods of inactivity. 
The reason of this fact, observed by Mr. McLain, is 
as follows : During the periods between visible feed- 
* Gaseous diffusion and oxidation are, of course, not really suspended, 
but only greatly reduced, enough remaining to keep up the cluster 
temperature given on page 518. 
k 
