TO THE ELEMENT A -RY EIBEES OF STEIPED MUSCLE. 
905 
necting or giving support to higher tissues, but results from changes occurring in the 
nervous tissue itself, and that the fine fibres of elastic tissue in indefinite connective 
tissue were actual nerve-fibres at an earlier period of life Thus a low form of tissue, 
which results from the natural changes taking place during the life and continual growth 
of the highest tissue, may form a basis of support for the latter. It becomes firmer as 
the organ or tissue advances in growth, but it does not exist at an early period of deve- 
lopment, nor is it a special tissue developed in a certain definite manner like tendon, 
true yellow elastic tissue, cartilage, muscle, &c. 
Conclusions. 
1. In certain muscles of the frog the distribution of dark-bordered nerve-fibres is 
pretty uniform in every part. Although in the case of the pectoral a greater number of 
nerve-fibres is distributed to the central part of the muscle, fibres may be traced from 
the large bundle almost to the extremities of some of the muscular fibres. Many 
branches which easily escape observation pass between the muscular fibres and their sub- 
divisions and supply neighbouring fibres, or are gradually lost in the connective tissue. 
2. Fine neiwe-fibres are most easily demonstrated on the external surface of the 
sarcolemma near the nerve-trunks ; but reasons have been advanced in favom* of the con- 
clusion that every elementary muscular fibre is more or less freely supplied with nerve- 
fibres throughout its entire length. Many of these fine nerve-fibres on the surface of 
the muscular fibre become gradually very faint, until from their extreme tenuity we are 
no longer able to follow them. 
3. Fine nerve-fibres in direct continuation with the dark-bordered fibres, and less than 
the or. of an inch in diameter, have been seen to divide into finer branches which 
have nuclei in connexion with them. 
4. The pale fibres delineated by KtiHNE and Kollikee, and by them considered 
single terminal fibres, consist of — 
a. Fibres about the 3500 ^ th of an inch in diameter, or less, resulting from the 
subdivision of the dark-bordered fibre. 
b. Fibres resulting from the subdivision of fine nerve-fibres ramifying in the sheath 
of the dark-bordered fibre, or situated external to it. 
5. Nuclei are found in connexion with — 
a. The dark-bordered fibre itself, near its terminal ramifications. 
h. The fine fibres which are the direct continuations of the dark-bordered fibres. 
c. The fine fibres in the sheath, or external to it. 
6 . The nuclei and delicate fibres above referred to are arranged so as to form net- 
works, the meshes of which vary much in size, situated with the capillaries on the 
external surface of the sarcolemna. The fibres of these networks are compound, and 
consist of finer fibres, which are distinct from, and do not anastomose with, each other. The 
* “ On the Distribution of Nerve-fibres to the Mucous Membrane of the Human Epiglottis,” in my 
‘Archives,’ No. XII. 1862. 
MDCCCXLII. 6 H 
