TO THE ELEMENTAET FIBEES OE STEIPED MUSCLE. 
899 
of the fibre, is so strong as to justify me in concluding that such an arrangement is actually 
present. If the nature of the tissue under examination be considered, and the extreme 
delicacy of the nerve-structure which has actually been demonstrated be fairly taken into 
account, no surprise will be felt that the network has not been actually demonstrated 
throughout the entire length of the large elementary muscular fibres of the frog. The net- 
work of fine fibres I have described exactly corresponds in its arrangement with networks 
which are demonstrated with comparative facility in the palate, bladder (Plate XLI. fig. 6), 
peritoneum, cornea, skin, and other situations in the frog. In the heart and tongue, 
networks also exist, but the fibres are very fine, and the meshes are wider. The network, 
composed of very fine fibres, lies on the same plane as the capillary vessels, and just upon 
the surface of the sarcolemma. The fine nerve-fibres often lie very near to the capillaries. 
The capillaries and the fine nerve-fibres with their nuclei are connected together by a 
membranous tissue so thin and delicate that its existence can only be proved after it has 
been coloured, or when some foreign particles have adhered to it. That it is, at least 
in some places, distinct from the sarcolemma, is easily proved in the muscles of the frog, 
in which animal the sarcolemma is very thick, as it can be stripped off leaving the sar- 
colemma. I have some specimens in which the muscular tissue has been withdrawn 
horn the tubes of the sarcolemma, so that the nerves can be seen very distinctly. From 
a part of the surface the thin membrane with nerves and capillaries has been withdrawn, 
leading the sarcolemma uncovered. In some specimens, on the other hand, the finest 
nerve-fibres and then nuclei seem in absolute contact with the sarcolemma, and appear 
to be adherent to or connected with it ; and I incluie to the opinion that some of the 
nuclei which appear imbedded in the sarcolemma are connected with the nerve-fibres. 
The pale fibres described by Kuhne and Kollikee are compound, and are composed 
of many very fine fibres, and they divide into bundles of fine fibres which form a network. 
Each ‘pale fibre’ consists (1) of a very fine fibre prolonged from the dark-bordered fibre, 
and (2) of very fine fibres continuous with those in the sheath of the nerve. The fibre 
which is the immediate prolongation of the dark-bordered fibre, as well as the fine fibres 
amongst which it runs, can be followed to nuclei, and often a lax network can be traced. 
The dark-bordered fibres are all continued as very fine fibres ; and the subdivisions of 
these, a short distance from the dark-bordered fibre, are too thin to be measured, even 
when examined by the highest powers made. The subdivisions of all nerve-fibres pass 
into fibres which have hitherto been included with the fibres of connective tissue. 
The same arrangement with regard to the distribution of the nerve-fibres is observed 
here as elsewhere. The fibres of the network are composed of numerous very fine fibres. 
Not one individual fibre can be followed for any distance ; but certain delicate fibres can be 
traced from one compound fibre to another, in precisely the same manner as the coarser 
fibres can be followed in a plexus. In fact, from aU that I have observed in examinuig the 
finest branches of the nerve-fibres in various tissues, I cannot but conclude that the general 
disposition of these finest fibres is the same . as that of the coarser trunks and fibres. 
In passing from the trunks towards the ultimate distribution, it might be said that we 
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