TO THE ELEMENTAEY FIBEES OF STEIPED MUSCLE. 
617 
fiition. There is no tubular membrane, medullary sheath or axis cylinder to be demon- 
strated ; neither is there any definite point at which the so-called white substance can 
be said to cease. The axis cylinder gradually loses its hard fibrous character (frog), and 
the white substance its peculiar refractive power and consistence. The whole fibre, as 
seen in my specimens, seems to consist of a very transparent and perhaps delicately 
granular substance, which can be shown to be composed of fatty and albuminous mate- 
rial. These appearances, are, however, produced by the action of reagents (chromic 
acid, bichromate of potash); for in their natural state, at least with the aid of the object- 
glasses we possess at present, the finer ramifications of the nerve-fibres and their nuclei 
are quite invisible. 
Of the Formation of New Fibres. 
New branches are continually being developed in connexion with the terminal nerve- 
fibres, and a certain number of old ones appear to undergo removal. The oval bodies 
dmde longitudinally and transversely, and the segment about to give rise to the new 
fibre is lengthened by elongation at each end, where the new fibre still remains in con- 
nexion with the original branch. Its nucleus divides transversely, and the length of the 
fibre thus goes on increasing. Traces of nerve-fibres which have ceased to perform any 
active office may be seen in the form of delicate fibres, which still remain in connexion 
with actual nerve-fibres. I am of opinion that the so-called connective tissue found in 
small quantity between the elementary fibres of muscle, and in some other situations, is 
produced in this manner. In many morbid alterations the so-called areolar, fibrous, or 
fibroid, or indeterminate connective tissue, certainly consists merely of the remains of 
other structures which have ceased to perform any active office, and cannot be com- 
pletely removed by absorption, 
Of Prejparing the Specimens. 
My specimens were obtained from preparations which had been previously injected 
with transparent blue injection. I found that without this operation it was not possible 
to follow the delicate nerve-fibres among the capillary vessels, or to distinguish these 
structures from each other with absolute certainty. I also adopted this plan as the only 
one calculated to introduce a preservative fiuid simultaneously to all parts of a. tissue, 
and with sufficient rapidity to prevent decomposition of the delicate structures under 
investigation. In this manner alone can alteration in chemical composition, in density 
and in refractive power of the preservative fluid employed, be prevented. The medium 
used was the same as that employed in my investigations on the anatomy of the liver 
Carmine solution was used for demonstrating the arrangement of the nuclei. The 
exact process employed is somewhat uncertain and complicated, and is probably 
capable of being rendered much more uniform in its results and more simple in its 
application. 
* Philosophical Transactions, 1856. The principles on which this fluid is employed will be found stated 
in the ‘ Microscope in its application to Practical Medicine,’ p. 63, and in papers published in the first 
volume of the ‘ Archives of Medicine,’ 1859, pp. 18, 152. 
MDCCCLX. 4 M 
