196 Macteay Mermoriat Vouume. 
of a nerve-fibre, and may be regarded as the flattened and expanded termination of 
the latter. It would thus seem to correspond in some of its morphological characters 
and in its probable significance, to the menisci or tactile disks described and figured 
by Ranvier* in the epidermis of the pig’s snout. These lens-like bodies are small, 
searcely larger than the surrounding epidermal cells of the base of the rod, and we 
have so far been unable to detect nuclei in the demilunes in spite of the clearness of 
their substance. A nerve-fibre, on approaching one of these end-organs, is seen to 
lose its medullated sheath shortly before joming the body, whilst the primitive 
sheath is continued so as to form a delicate capsule for the organ. The structure of 
these end-organs may be seen by referring to fig. 10, Pl. xxv., and figs. 18, 19, and 
fo} 
20, Plate xxvi. The last figure is semi-diagrammatic. 
The principle of this arrangement is similar to that which obtains in the 
constitution of a Grandry’s corpuscle. But in the first place the lenticular bodies 
here described are intra-epithelial, and not sub-epithelial like Grandry’s. Secondly, 
the average size of the latter corpuscles, as given by Krause,t is 67», which is five 
times the size of our “lenticular bodies.” Lastly, a well-marked vesicular nucleus 
and nucleolus are always to be seen in the component cells of the corpuscles of 
Grandry. 
The third species of sensory nerve-termination with which the rod-organs are 
provided consists of a rich supply of fine terminal fibrils traversing the shaft of the 
rod from base to surface. These fibrils were observed and described by Mr. Poulton, 
but he failed to recognise their nervous character and connections. 
Those medullated nerve-fibres which do not end either im the Pacinian-like 
bodies or in the “lenticular bodies,” enter the base of the rod in two fairly distinct 
series, a central and a peripheral. The fibres of the central group are pretty closely 
associated with the fibres for the lenticular bodies, and enter the rod by piercing its 
flat basal surface. Here they find their way for a short distance between the 
epithelial cells, being directed towards the axis of the rod. They then suddenly lose 
their white sheaths and the naked axis-cylinders, which are here frequently branched, 
and are continued peripherally along the axis of the shaft, forming a bundle of 
delicate parallel fibrils (figs. 11 and 21, Plates xxv. and xxy1.). 
In transverse section this bundle of fibrils is seen to occupy a circular area in 
the centre of the core, corresponding to the axial region of the epithelial conical 
laminz already described (fig. 13, Pl. xxv.). In their course the fibrils of this 
central or axial bundle must traverse the inner portion of the core as represented by 
* Compt. Rend. 1877. Tome LXXXV. 
+ Krause, loc. cit. S. 87. 
