72 
MUSCULAR SYSTEM. 
the whole muscular fibre like a wave — the contractioji 
7 iuave — the progress of which is noticeable by the 
thickening shifting along the fibre, the part behind 
resuming its previous diameter. 
In the central part of the fibres are formed nuclei 
of protoplasmic corpuscles, called muscle corpuscles. 
These become converted into muscular substance, at 
the expense of which new fibres are formed, or fibres 
already formed become thickened. 
Muscles are sometimes made up of bundles of 
fibres (Fig. 33, a), and end in tendons, which vary in 
length. In colour they are nearly white, but some 
are pale red. 
The number of muscles in a bee is very large and 
their power very great, the largest muscles being found 
in the thorax. These are shown in Fig. 21 (<?, r, 
and d)^ and it will be seen that they nearly fill up the 
cavity. 
Powerful muscles are also provided for the jaws 
(Fig. 51, ^), which are required to knead the wax. 
M. Plateau (43), who has studied the power of 
traction in insects, found that the bee could draw 
twenty times the weight of its body. The lifting 
power he found to be equal to the weight of its body. 
The average weight of a man is 142 lbs., and his power 
of traction, according to Regnier, is only 124 lbs., or 
not nearly the weight of his body. This will give an 
idea of the enormous strength of a bee in proportion 
to the size of its body. 
In bringing different parts of the body into action 
different muscles are brought into play. Newport (i 16) 
