14 DR. BEALE, ON NERVE-FIBRES. 
It might be asked, if the author holds that there is a com- 
plete circuit in the case of the afferent and another in that of 
the efferent fibres distributed respectively to the tissues and 
small arteries, or if the afferent and efferent fibres form 
part of the same circuit, in which case an impression might 
be transmitted to, and a motor impulse start from, the same 
ganglion-cell; but he postpones the consideration of this part 
of the question. 
The fine nucleated fibres distributed in the neighbourhood 
of capillary vessels, and to tissues which do not receive a vas- 
cular supply at all, form, in the tissues of the frog generally, 
fine trunks consisting of several very fine fibres, and these 
unite to form larger trunks, which, as a general rule, are 
accompanied by one or more dark-bordered fibres, but in the 
bladder, in the heart, and also in the mesentery, large trunks 
exist which are composed entirely of these very fine fibres, 
and at certain points plexuses are formed. In the cornea the 
individual fibres are not so distinct, nor are the fibres so 
decidedly separated from each other as in the drawing accom- 
panying the author’s paper. Many seem to be in course of 
splitting, an appearance more like that seen in the sympa- 
thetic branches of birds and mammalia, where the fibres 
in a trunk appear to be connected together forming 
bands.* 
It is quite certain, therefore, that the fine fibres above 
described are independent of the dark-bordered fibres. But, it 
will be asked, are all the fine fibres in the trunks—for example, 
in those represented in the figure—afferent fibres? Ina trunk 
passing from the cornea, doubtless, all are of this nature, but 
Dr. Bealehas seen many such fibres passing amongstthemuscu- 
lar fibre-cells of the bladder, and also to the contractile coats 
of the small arteries, so that at least in this case it is probable 
that some of the fibres entering into the formation of the 
plexus figured, are afferent and others efferent. There are no 
characters by which one class of fibres can be distinguished 
from the other. Amongst the nerves forming the large bundle 
which supplies a limb, some bundles of fine fibres, which pro- 
bably belong to the same class, are to be found, but the 
author has never seen large bundles of very fine fibres like 
those in the bladder and mesentery, in the voluntary muscles. 
Such bundles, however, do exist in connection with the heart. 
The bundles of fine fibres at their peripheral distribution 
form plexuses and networks. The author has never seen any 
termination in any case. The fine nerve-fibres distributed to 
* The arrangement of the nerve-fibres in the cornea of various animals is 
fully described in an elaborate paper by Dr. Ciaccio, of Naples, in No. XI 
of this Journal. 
