472 
DR. E, KLEIN. 
fibrils, I consider imperfect, and Waldeyer^s assertion must 
therefore be taken to have the value of negative evidence 
only. That the reduction of the gold in Izquierdo’s speci- 
mens has not been complete is further proved by his saying 
(1. c., p. 29) that, in vain have w^e searched in the epithe- 
lium for the cells of Langerhans, 'which Ribbert pretends 
to have recently found.^^ These cells — elongated cells with 
very many finer and thicker branched processes — it is true, 
are not met with in ordinary specimens, but in those in 
which the reduction of the gold has been complete they are 
very conspicuous by their colouration and size. Their number 
generally varies in the middle and superficial layers of the 
epithelium in different places and their processes, although 
crossed by the intraepithelial nerve-fibrils, appear nowhere 
connected with them. 
The assertions of Inzani (quoted by Izquierdo, 1. c., 
p. 16) about special terminal ends situated amongst epithe- 
lial cells of the deepest layer and possessed of minute fibrils, 
as well as those of v.Thanhoffer (^Virchow’s Archiv,^Band 63, 
1875) about the fine nerve-fibres terminating in so-called 
tactile corpuscles, situated between the cells of the deepest 
layer of the epithelium, are obviously due to imperfet speci- 
mens. This is well illustrated by t^he fact that Thanhoffer 
did not see any nerve-fibrils beyond the deepest layer of 
cells. To a similar cause, viz. to imperfect specimens, must 
be also attributed the assertions of Beale about the absence 
of nerves in the epithelium. Beale did not see any nerve- 
fibres in the anterior epithelium of the cornea, but then 
this observer did not make use of the chloride -of-gold 
method. 
The last point which I wish to discuss here is the termina- 
tion of the nerve-fibrils in the substantia propria. As is 
well known, Kiihne was the first to maintain that in the 
frog^s cornea the finest fibrils terminate in connection with 
the processes of the corneal corpuscles. The number of ob- 
servers who made this a special point of investigation, 
although great, range themselves in those who confirm 
Kuhne, Moseley (this Journal, July, 1871), Konigstein (^Sitz- 
ungsber. d. K. Akad. in Wien.,’ 1877, Band 76), Izquierdo 
(1. c., p. 25). and Waldeyer (1. c., p. 378) ; both these last- 
named observers assert, however, that some fine fibrils termi- 
nate also free in the substantia propria. Then those who 
simply deny such a connection, and accept a free ending of 
the fine nerve-fibrils in the substantia propria, Kolliker (1. c.), 
Kngelmann (1. c.), Dwigbt Monthly Micr. Journal/ 1869), 
