148 
Beekeeping 
While bees can convert sucrose (cane sugar) into levulose 
and dextrose and can digest maltose, they cannot digest 
certain other sugars. There is also considerable evidence 
that dextrine cannot be digested and that the presence in 
the food of unusual amounts of dextrine may produce the 
condition known as dysentery. It has also been found 
that certain proteids which have been used as substitutes 
for pollen cannot be digested. The alimentary canal of 
the bee, therefore, appears to be a highly specialized system, 
incapable of any considerable flexibility. Bees would evi¬ 
dently fail to be nourished by the mixed diets of many 
other species, which is additional argument against at¬ 
tempted homologies with human digestion. 
CIRCULATION 
When the products of digestion are absorbed and traverse 
the alimentary canal wall, they must be carried to the 
various tissues for assimilation. This is done by means 
of the blood. In the higher animals blood is normally 
confined in blood vessels which carry it throughout the 
body, but in the bee, as in other insects, the blood bathes 
the various organs, filling up the interstices between them. 
These spaces may, however, be so arranged that the blood 
flows in definite channels or sinuses. The blood is further 
confined to definite paths by membranes stretched across 
the dorsal and ventral walls of the abdomen (DDph and 
VDph, Fig. 78) which bound the chief sinuses. These 
diaphragms have a rhythmical motion and assist in the 
circulation of the blood. The heart (Hi) is located dorsal 
to the dorsal diaphragm, this sinus being therefore known 
as the pericardial chamber. The heart is a long muscular 
tube consisting of four chambers lying in the third, fourth, 
fifth and sixth segments of the abdomen. In each of these 
segments is a valvular opening (ostium, Ost ) on each side 
for the admission of blood from the pericardial chamber, 
and there are also segmental valves to prevent a backward 
