150 Beekeeping 
the thorax and opening by simple branches into the head 
cavity. 
The blood of the bee is a colorless liquid containing certain 
corpuscles, but no red ones such as are found in mammals. 
The blood is forced through the heart and aorta to the head 
cavity. It then flows backward through the sinuses of the 
thorax into the ventral sinus of the abdomen. Pumped 
backward by the pulsation of the ventral diaphragm, it 
flows through various definite cavities between visceral 
organs in the abdomen and into the pericardial cavity, 
from which it again enters the heart through the ostia. In 
its passage through the sinuses about the viscera, the blood 
takes up the food which has passed through the walls of 
the alimentary canal. This nourishment is promptly 
carried to all parts of the body by the circulation. 
METABOLISM 
It is not proposed at this time to enter into a long dis¬ 
cussion of the ways by which each organ is rebuilt as needed. 
In the general discussion of the cells which make up the 
various organs (p. 94), it was stated that each cell is ca¬ 
pable of taking up nourishment and of building this into 
protoplasm. It also utilizes oxygen furnished by the res¬ 
piratory processes. To this process the name anabolism 
is given. Not all cells require the same constituents of the 
food presented or the same amount of oxygen, but by some 
mysterious process each cell is enabled to choose those parts 
which it needs. Similarly, as the activities of the cells 
progress, protoplasm is broken down and waste products 
are formed : this we know as katabolism. The final products 
of katabolism are carbon dioxid and water, together with 
various more complex chemical compounds usually con¬ 
taining nitrogen, such as uric acid and urea. The elimina¬ 
tion of the more complex waste products is discussed under 
excretion. 
