12 DR. BEALE, ON NERVE-FIBRES. 
number in many sensitive surfaces, as, for example, just 
beneath the epithelium of the mucous membrane of the 
fauces, have been and are still considered by many authori- 
ties to be connective tissue-corpuscles. Not a few observers 
in this country as well as on the continent, following Vir- 
chow and his school, consider that they communicate with 
each other by tubes, and thus form a new canalicular system 
for conveying nutrient juices.* 
The so-called nuclei are never terminal, but a fibre always 
passes from each nucleus in two or three different directions. 
Not only nuclei, but nerve-fibres have by many observers been 
included under the head of connective tissue. Nor, indeed, 
can these fine terminal nerve-fibres be demonstrated in fibrous 
tissues in which they exist in great number by the ordinary pro- 
cesses employed in demonstration. They can only be seen in 
exceedingly thin sections, and with the use of the highest 
powers. Not only are nerve-fibres present in certain forms 
of connective tissue, but there are many fibrous tissues des- 
titute of vessels to which nerves are distributed. In the cor- 
nea, in the fibrous tissue about the pericardium, the pericardium 
itself, and the bundles of fibrous tissue in connection with 
the vessels and various organs in the abdominal cavity of the 
frog, nerve-fibres are very numerous. 
Dr. Beale has succeeded in demonstrating nerve-fibres in 
connection with the vessels in so many tissues of the frog, and 
of certain mammalia, that he is strongly inclined to the 
opinion that in vertebrate animals nerve fibres exist wher- 
ever vessels are present. These remarks apply not only to 
the smallest arteries and veins, but also to the capillaries.+ 
Since the capillaries are devoid of muscular fibre-cells, and 
do not possess contractile power, it is probable that these 
fine nerve-fibres associated with the capillary vessels are 
afferent fibres. 
In the papille of the frog’s tongue, for example, besides 
the bundle of sensitive nerve-fibres passing up the central 
part of the papillze, there are very fine nerve fibres distributed 
to the vessels, and some fine fibres in the connective tissue 
external to the vessels. Similar fibres exist in the small 
papilla, to which neither vessels nor dark-bordered nerve- 
fibres are distributed. The nuclei connected with these 
fibres are about the 1-300th of an inch or more apart. Now 
these fibres are not ordinary fibres of connective tissue, for 
the author traced them into undoubted nerve-fibres. More- 
* See a paper on the “ Distribution of the Nerve-fibres to the Mucous 
Membrane of the Human Epiglottis.” ‘Archives,’ vol. ili, p. 249, 
+ See figs. 5 and 9, in plate xxiii, ‘ Phil. Trans.,’ 1860. 
