kukenthal: astylosternus robustus. 375 



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 (n). 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. 



