10 
There seems to me to be so much strong evidence in 
favour of the last view, that I venture to express a decided 
opinion that this is the truth. In many specimens I have 
seen, and most distinctly, tbe delicate network of fibres re- 
presented in PL II, fig. 3, continuous with the fine nerve- 
fibres in the summit of the papilla, and I have demonstrated 
the continuity of these fine fibres with the matter of which 
the outer part of these peculiar cells consists (Pis. I & II, figs. 2, 
3, 6). I have also seen what I consider to be nerve-fibres in 
the intervals between some of these cells (fig. T). Upon 
the whole I am justified in the inference that there is a 
structural* continuity between the matter which intervenes 
between the masses of germinal matter at the summit of the 
papilla and the nerve-fibi'es in its axis, and I consider that 
an impression produced upon the surface of these peculiar 
cells may be conducted by continuity of tissue to the bundle 
of nerve-fibres in the body of the papilla. These peculiar 
cells in the summit of the papilla cannot therefore be re- 
garded as epithelium, and the mass constitutes a peculiar 
organ which belongs, not to epithelial structures, but to the 
nervous system. 
Although there can be no doubt whatever as to the exist- 
ence of an intricate and exceedingly delicate nervous net- 
work or plexus at the summit of every papilla, such a plexus 
might be connected with the nerves according to one of two 
very different arrangements : 
1. The plexus might be formed at the extremity of a nerve 
or nerves, as represented in diagram (PI. IV, fig. 17). 
2. The plexus might form a part of the course of a nerve 
or nerves, as represented in diagram (PI. IV, fig. 18). 
If the first be true, the network must be terminal, and im- 
pressions must be conveyed along the fibre, of which the 
plexus is but the terminal expansion, direct from periphery 
to centre. If the second arrangement is correct, the network 
forms a part of a continuous circuit or of continuous circuits. 
I believe the division of the nerves at the base of the papilla, 
already adverted to, is alone sufficient to justify us in accept- 
ing the second conclusion as the more probable ; but when 
this fact is considered with reference to those which I have 
adduced in my paper published in the c Transactions ’ for 
1863, and that in the ‘ Proceedings 3 for June, 1864, and the 
observations published in several papers in vols. ii, iii, and 
iv of my ‘ Archives/ and in the Croonian Lecture for 1 865, 
I think the general view in favour of complete circuits is 
the only one which the anatomical facts render tenable. The 
mode of branching and division of trunks and individual 
fibres is represented in PI. IA r , figs. 20, 21, 22, 23. 
