KUKENTHAL: ASTYLOSTERNUS ROBUSTUS. 315 
There is a quite conspicuous blood vessel running along the axis 
of the cutis papilla and other smaller blood vessels are found in the 
surrounding substance of the cutis. The whole papilla is built up 
of a dense connective tissue, whose fibres run for the most part either 
in transverse or in longitudinal directions. Chromatophores are 
numerous, being especially abundant at the base of the appendage. 
Dr. Gadow denies that there are nerves or nerve-terminations in 
these appendages and therefore maintains emphatically that the 
function of sensory-organs is wholly excluded from these appendages. 
In opposition to that, my own observations have convinced me, that 
there are both nerves and nerve-terminations in these appendages, 
and that therefore they do serve as sensory organs. 
Owing to the fact that the objects were preserved in alcohol, the 
impregnation by Bielschowsky’s method did not work well; but I 
finally succeeded in observing large nerves (Fig. B) entering the papilla 
from its base, and in finding some tactile cells (tc.) of the same shape 
as those described by Merkel in other frogs. They were situated in 
the grooves between the epidermal ridges. Here the epidermis is 
very thin. The tactile cells appeared as rather flat protoplasmatic 
bodies with a quite distinct nucleus, and their broader sides were 
parallel to the outer surface of the epidermis. Each of these 
tactile cells was provided with an axis-cylinder, which ran quite 
close to the surface of the epidermis, but in the cutis tissue beneath 
it, and were united proximally into a common nerve fibre (x). The 
nerves of these tactile cells therefore come from the outer, not from 
the deep, surface of the cells, and this agrees very well with some 
statements made by Merkel (’80, p. 109) regarding the innervation 
of tactile cells. The condition of my material did not allow me to 
carry this investigation further, but from the evidence I have, I 
maintain that these appendages contain nerves and nerve termina- 
tions and, therefore, that they must have something to do with 
sensory functions. Besides these, there may be other functions, 
it is true, as is suggested by the presence of glands. 
It is also a striking fact that these appendages appear only on 
those areas of the surface where, according to Merkel (’80, p. 108, 
Taf. IX, Fig. 2), in other frogs these tactile cells (“'Tastflecke’’) 
form aggregations. | 
The results, then, of this investigation are, that these appendages 
in Astylosternus robustus appear only in the males during the mating 
season, and are to be considered as secondary sexual organs of a very 
peculiar hair-like shape, originating from tubercles of the skin, and 
that they are charged with sensory functions. 
