Witson ann Martin—Rod-ike Tactile Organs in the Muzzle of Ornithorhynchus. 195 
The nerve apparatus with which each rod-like organ is equipped consists of the 
thick leash of medullated nerve-fibres already referred to, together with the various 
terminations of these fibres, which end in three distinct ways. Two of these different 
kinds of nerve-endings are associated with the presence of special end-organs, while 
fibres of the third class of ending terminate in free fibrils in the manner subsequently 
to be described. 
The first method of termination is that described by Poulton,* viz., in four or 
five small Pacinian-like bodies. We may quote from this author as follows -— 
“Inferiorly these rods terminated in a convex surface, against which a group of 
small Pacinian bodies was always collected. Horizontal sections showed that this 
association was invariable, and that the groups usually contained four, five, or six 
Pacinian bodies. The Pacinian bodies were quite similar to those in the tongue of 
Ornithorhynchus.+ They are arranged with their sides parallel to the surface from 
which the pressure is communicated.” 
In respect of the Pacinian-like bodies, we have very little to add to the 
descriptions of this author in the journals above-mentioned. We have, however, 
noticed that very frequently, in addition to the four or five small Pacinian-like 
bodies situated in the position mentioned by Poulton, one or more bodies, similar as 
regards structure, but of a size two or three times as great, are found lying in the 
dermis, a short distance from the base of the organ (figs. 7, 8, and 9, Pl. xxv.). 
These Pacinian-like bodies are substantially identical with those described by Corti 
as occurring in the tongue of the elephant, and figured by Krause in his papers on 
the nerve-endings in terminal corpuscles, under the name of ‘“ Endkapseln.” 
The second mode of nerve-ending is one which has not been noted by Mr. 
Poulton. Some of the nerve fibres proceeding towards the base of the rod-organ, 
and passing in close proximity to the Pacinian-like bodies, enter the base of the rod 
to end in a number of specialised organs which do not precisely correspond in 
character to any other form of nerve end-organ known to us. These bodies, which 
we have accustomed ourselves to call ‘lenticular bodies,” are oval in shape and about 
13 in their longest diameter, and appear to consist essentially of two clear vesicular 
cell-like structures, shaped somewhat like plano-convex lenses. Between the 
approximated plane surfaces of these is placed an intermediate layer, forming a disk 
or meniscus, which stains deeply with gold chloride, while the other elements remain 
for the most part untinged. This disk is in direct continuity with the axis-cylinder 
* Loc. cit. 
+ Quart. Jour. Micro. Sci. July, 1883. 
+ Zeitschrift fiir wissenschaftliche Zoologie, 1854, Bd.V. S. 89 
§ Arch, fiir mikroskopische Anat. Bd. xrx. S. 61, u. fig. 8. Taf. 11. 
