TRANSACTIONS OF MICROSCOPICAL SOCIETY. 
DESCRIPTION OF PLATES XIV & XV, 
Illustrating Dr. Beale's observations on the Distribution of 
Nerves to Insect-Muscle (page 94). 
The elementary muscular fibres represented in fig. 1 are of large size, and 
consist, for the most part, of five subdivisions, all included within the tube of 
the sarcolemraa. But, in some cases, tracheae and nerve-fibres dip down in 
the intervals between the subdivisions. Sometimes the subdivision is dis- 
tinct at the two extremities of the muscle without existing at the central 
part, in which case fine nerve-fibres and tracheae pass around the subdivided 
portions, but do not perforate the central part of the muscle. In all cases 
branches of nerve-fibres and tracheae pass over the entire surface of the 
muscle. The appearances described are observed in fully developed muscles, 
not in young ones. It would appear as if there was first the tube of the 
sarcolemma, which formed subdivisions, and exhibited a tendency to the for- 
mation of subordinate tubes ; or the sarcolemma of these muscles of the 
maggot might be regarded as a transparent matrix, in which fine elementary 
Tfiuscular fibres, connected together in the central part, were imbedded, 
)ust as the so-called tubular membrane of nerve-fibre often appears as a fine 
transparent matrix, in which several dark -bordered nerve-fibres are im- 
bedded.* 
The general course of the nerve-trunks is well seen in this figure. They 
cross the muscles at right angles, and give off branches which may be 
raced to the surface of the sarcolemma. Tlie trunks do not divide and 
subdivide into branches, each of which is distributed to a muscle, as has 
been represented ; but they pass completely over several muscles, receiving 
several branches in their course, and these seem to be composed of the ultimate 
ramifications of numerous finer bundles, which are distributed to contiguous 
muscles. 
The arrangement and number of the " nuclei," or masses of germinal 
matter of the muscle, are well seen in the part of this fig. 1 to the left of 
the observer. The nerve-nuclei are much smaller than those of the muscle. 
Some are represented in fig. 2, which is very highly magnified. 
rig. 2 shows that the very fine- fibre, which may be considered as terminal, and 
which seems lost upon the surface of the sarcolemma in fig. 1, really consists 
of exceedingly fine nerve-fibres, which, as they approach the larger trunk, 
divide into two bundles {a, a) which take opposite courses in the trunk. This is 
fact of the utmost importance, and, as it is constantly observed, forms a 
strong argument against the view which supposes that nerve-fibres termi- 
nate in free ends, while it is in favour of the conclusions to which I have 
been led from many different inquiries as to the existence of complete 
circuits. My observations all point to one conclusion — that a nerve never 
ends, and that nerve-fibres invariably form complete circuits. 
The further ramifications of the nerve, and its subdivision into extremely 
fine fibres, which ramify upon the surface of the sarcolemma, are represented 
* See 'New Observations on the Structure of Nervous Centres,' &c. 
Churchill and Sons, 1864. Also a paper in No. XIY of my 'Archives.' 
