Charles Russell Bardeen 241 
lowed in muscles like the latissimus dorsi. Nussbaum has shown that 
the distribution of nerves belonging to a muscle indicates the direction 
of development of that muscle. Popowsky’s interesting work on the 
development of the facial nerve illustrates this principle well. In addi- 
tion to this active extension of nerve distribution on or within a muscle, 
the bundles of muscle-fibres comprising it may shift their relative posi- 
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Fic. 8. A portion of a segment of the rectus muscle of a pig embryo 89 mm. 
long. An intramuscular nerve may be seen distributing branches in the loose 
mesenchyme separating the bundles of muscle-fibres, 720 diam. 
tions, as in certain segments of the rectus abdominis of the larger mam- 
mals, and the muscle as a whole may shift its position in relation to 
other parts of the body, and thus the nerves may be passively altered in 
their relations. 
In addition to the nerves furnished to the muscle-fibres during devel- 
opment, nerves are also furnished to various sensory endings lying in 
the muscle, to its associated skeletal apparatus and to the blood-vessels. 
