60 
BLOOD CIRCULATION. 
observers have recognised the fact that a certain 
warmth is always found in a cluster of bees, even in 
winter. 
The temperature, as Newport (120) has shown, is 
intimately connected with the activity of respiration and 
the agitation of the bees. It is by close clustering that 
they can raise the temperature they find necessary for 
comb-building. In 1878 we carried out a series of 
experiments to test the amount of heat in a cluster 
of bees in winter, for Newport had stated that it 
fell sometimes below freezing point. Our experiments 
were carried out with extreme care on four hives in a 
bee-house, and although the outside temperature and 
that in the bee-house frequently fell below freezing 
point, on only two occasions did the temperature of 
the cluster fall below 60 degrees. On the occasions 
when we found it below this, the hives were opened, 
and revealed the fact that the cluster had moved 
away and left the thermometer exposed. 
The temperature inside the cluster ranged from 60 
to 70 degrees Fahrenheit. At different seasons the 
temperature inside the hive varies, and Newport found 
that during the swarming season more heat was pro- 
duced, even with a lower external temperature, than 
in the month of August. In the former case he found 
it as high as 96° Fahr., with an outside temperature 
of 66° Fahr., whilst in the month of August it is 
seldom more than 80°, or perhaps 86°, even in the 
middle of the day, when the temperature is often more 
than 78° Fahr. Less heat is in reality produced from 
the same volume of air consumed at the high tempera- 
