612 
PEOrESSOE BEALE OX THE DISTEIBniOX OE XEETES 
General Ojiinion entertoined. 
The general opinion at the present time seems to be that nerves terminate upon 
the elementary fibres of voluntary muscle by free pointed extremities. Kolliexe con- 
siders it probable that the elementary fibres are only touched by the nenns at distant 
points, while some conclude that many fibres, or even parts of a muscle, are not brought 
into actual contact with nerve-fibres at all. As the results of my inquiries differ so 
entirely from those of other observers, I think it right to say that my observations have 
been very frequently repeated with great care, and upon several different vertebrate 
animals (man, dog, rat, guinea-pig, mouse, greenfinch, frog, tadpole, gudgeon, minn ow, 
&c.). Several of the specimens from which my conclusions have been deduced ai'e pre- 
served permanently, and can be examined by all interested in this inquiry. 
Of the Distribution of the Nerves to the Elementary Fibres. 
My observations lead me to conclude that nerves are distributed to every elementary 
fibre of all voluntary muscles of man and vertebrate animals. The elementary fibres of 
some animals are much more abundantly supplied with nerves than those of others. 
The muscles of the mouse receive a larger supply than those of man. Generally, it 
may be said that the muscles of reptiles and fishes are sparingly supplied with nerves irr 
comparisorr with those of mammals and birds. I have foirrrd that in the same] animal 
a greater number of nerve-fibres are distributed to some muscles than to others. Thus 
the elementary fibres of the tongue of the mouse receive a larger supply than those of the 
diaphragm, and the latter a much larger supply than the muscles of the system generally. 
The sarcolemma of the elementary fibre of the tongue and diaphragm of the mouse 
seem to be completely covered with nerves and vessels. The nerves for the most part 
run close to the capillaries, and it is not possible to separate these structures from each 
other without destroying them. Some of the nerve-fibres cross the elementary fibre 
transversely, others obliquely, while some .run longitudinally on the central or lateral 
aspects of the fibre. In fiivourable specimens the nerves may be seen to divide on the 
surface of the sarcolemma. The ultimate fibres are, however, of such extreme delicacy, 
that a little careless manipulation, pressure, or a very slight alteration in the density of 
the fiuid in which they are immersed, or in its refractive power, renders them quite 
invisible or destroys them altogether. I have not been able to follow an indiridual 
fibre for any great distance in consequence of the constant change in its coiu'se. These 
observations show that it is possible for an elementary fibre to be supplied with nerves 
from several different sources. It is not possible to decide, from the course of a single 
nerve-fibre, whether it is coming from, or passing towards, the nervous centre. Many 
fibres, apparently passing from one point, can be followed for some distance in opposite 
directions. The appearance of the nerve-fibres on the elementary muscular fibre difiers 
shaped cells on its surface. These are very difficult to demonstrate, but I hare been able to preserve some 
specimens which show this point very clearly. 
