8 
1. That the bundle of nerve-fibres distributed to a papilla 
always divides into two bundles which pursue opposite direc- 
tions. The division of the bundle may take place just at the 
base of the papilla, or at some distance from it, but it always 
occurs (PI. I, fig. 1). 
2. Fine pale nerve-fibres pass from the same trunk of dark- 
bordered fibres as that which gives off the bundle of nerves 
to the papilla. The fine fibres ramify — 
a. Amongst the muscular fibres of the tongue (figs. 1, 9). 
b. Upon the vessels (fig. 1, i, i, i). 
c. In the connective tissue of the tongue generally, and 
also in the simple papillae (fig. 1, d, e ). 
The division of the bundle at the base of a papilla is 
shown in PI. I, fig. 1, and in PI. Ill, fig. 10, is a diagram 
to indicate the manner in which the nerve-plexuses at the 
summits of the papillae are connected together by commissural 
fibres. Thus, in action the papillae may be associated to- 
gether. The bearing of this arrangement upon the existence 
of complete nervous circuits is discussed in my ‘ Archives,’ 
vol. iv. The bundle in the central part of the papilla con- 
sists of dark-bordered fibres, which frequently cross and 
interlace with one another in this part of their course. They 
vary much in diameter, some being so fine as scarcely to be 
visible. 
As the bundle passes towards the summit of the papilla, 
the individual fibres divide and subdivide into finer branches. 
Now, as I have before remarked, nerves so near their distri- 
bution as these do not usually possess an axis-cylinder as a 
structure distinct from the white substance. The white sub- 
stance does not abruptly cease, while the axis-cylinder is 
alone prolonged onwards by itself as is often described, but 
the entire fibre divides and subdivides. In fact dark-bordered 
nerve-fibres, near their ultimate ramifications, always consist 
of fatty albuminous material embedded in a transparent matrix 
of connective tissue. The “ tubular membrane,” “white sub- 
stance,” and “ axis-cylinder” can never be demonstrated as 
distinct structures near the peripheral distribution of nerves. 
The “ tubular membrane ” is nothing more than the trans- 
parent matrix in which one or more nerve- fibres are em- 
bedded. 
The dark-bordered fibres divide into finer fibres about the 
level of the ring or half-ring of capillaries at the summit of 
the papilla. As the fibres are exceedingly transparent, they 
are usually lost from view about this point. For example, 
Hartmann’s figures convey the idea that distinct dark- 
bordered fibres can be followed as high as this point, but 
