BLOOD CIRCULATION. 
59 
"rhese last are the ends of the finest tracheal ramifi- 
cations, the peritoneal * membrane of the tracheae, 
uniting with the external membrane of the pericardial 
cells. 
By this discovery of Graber's it is seen that the 
blood can be supplied with oxygen by the numerous 
tracheae diffused throughout the body, and also, being 
oxygenated at last in close proximity to the dorsal 
vessel, it enters it to be propelled to the brain, and 
from thence to every other part of the body. 
The blood of the bee, like that of other insects, is 
colourless, and contains white corpuscles, which are 
less numerous than those found in the red blood of 
vertebrate animals. They have a cellular character, 
containing protoplasm and a nucleus surrounded by 
granular matter. They are analogous to the white 
blood corpuscles of vertebrates, and are constantly 
changing their shape, like amoebae, and are therefore 
called amoeboid. Sometimes they are round, then 
ellipsoid or boat-shaped, or ragged at the edges, or 
pointed, and even star-shaped. 
Newport (120) and Graber (52) remarked that 
the speed of circulation altered with the temperature, 
and also that this has much to do with the number of 
pulsations of the heart, which cease at freezing point, 
and are more and more active in proportion to the 
rise in the temperature. The blood of the bee has a 
certain amount of specific or animal heat. Ancient 
* Belonging to the peritoneum, a thin, smooth, serous mem- 
brane, investing the whole internal surface of the abdomen, and 
more or less all the viscera contained in it. 
