Charles Russell Bardeen 239 
line. The centre of these bundles may be seen to correspond closely to 
an area of distribution of motor-endings, here represented as black dots.’ 
The most important problem connected with the development of the 
nerves belonging to the muscles is the mode of distribution of the nerves 
within the muscle. Mainly on theoretical grounds Firbringer, Hisler 
and others have supported the view that the nerve and muscle cells are 
Fic. 6. A portion of the nerve-plexus distributed to the transversalis musculature 
of a guinea-pig embryo 814 cm. long. 11 diam. 
closely associated from a period of development long preceding the differ- 
entiation of the permanent muscles. No good histological evidence has 
been brought forward in support of this view. On the contrary, the 
independent development of the nerves belonging to the muscles may be 
followed step by step from the primary embryonic nerves up to the union 
3 Mays (1884), in his splendid contribution to the subject of the intramuscular distri- 
bution of nerves, has called attention to the fact that muscle-fibres are often inner- 
vated approximately midway between their extremities. Bardeleben and Frohse have 
made valuable studies of ‘the nerve distribution in human muscles, but the methods 
used did not enable them to expose the full richness of the intramuscular nerve dise 
tribution. Frohse was able to trace nerves to muscle bundles a millimeter in 
diameter. Nussbaum has lately given a good review of the more recent work on 
the relation of nerves to muscles- 
