906 
PEOrESSOE BEALE ON THE DISTEIBTJTION OE NEEVES 
fine fibres continued from some of the dark-bordered fibres, as well as those ramifying in 
the sheath of the nerves, may sometimes be followed over six or more elementary muscular 
fibres, and form, with other fine branches, networks, many of the meshes being as wide 
as a muscular fibre. 
7. Fine nerve-fibres, with nuclei connected with them, exist (not unfrequently to the 
number of four or five) in the sheath of dark-bordered nerve-fibres near their distribu- 
tion; and some are also found external to what appears to be the outline of the sheath. 
Some of these result from the subdivision of a dark-bordered fibre. These fine fibres and 
their nuclei have been included hitherto under the head of ‘ connective tissue.’ 
8. The connective tissue around the elementary muscular fibres, and in connexion with 
the nerve-fibres, is composed of — 
a. Nuclei which might have taken part in the formation of the nerve-fibres, but 
which have degenerated, and a low form of fibrous tissue has alone been produced. 
h. Fibres and nuclei which were once active and formed an integral part of the 
nervous system, but which have grown old, and have been replaced by new nuclei 
and fibres. 
c. The remains of altered and wasted vessels and nerve-fibres distributed to them, 
and perhaps wasted muscular fibres themselves. 
9. The nerves distributed to the voluntary muscles of the frog do not terminate in 
free ends, but there is reason for believing that complete nervous circuits exist. 
10. In all cases the fibres resulting from the division of the ordinary nerve-fibres aie 
so fine that many cannot be seen with a power magnifying less than a thousand diameters, 
and there is evidence of the existence of fibres which could only be positively de- 
monstrated by employing a much higher magnifying power. It is probably by very 
fine fibres alone and their nuclei, that the tissues are infiuenced. The ordinary nerve- 
fibres are only the cords which connect this extensive peripheral system (which has been 
traced in different tissues far beyond the point to which the dark-bordered nerve-fibres 
can be followed) with the central organs of the nervous system. 
11. The facts and conclusions above stated, with reference to the distribution of neive- 
fibres to the voluntary muscles of the frog, are in accordance with the arrangement of the 
finest nerve-fibres demonstrated in many other tissues of the same animal, and agree with 
many appearances observed by the author in connexion with the peripheral distribution 
of the nerves, not only in certain tissues of man and the higher animals, but also in in- 
vertebrate animals. 
12. The distribution of the finest branches of the nerve-fibres can only be demon- 
strated in tissues which have been immersed in fiuids which refract highly, as syrup or 
glycerine. 
