TENTACLES OF BLENNIUS GATTORUGINE. 299 



a fine though blunt-ended hair-like process. They closely resemble olfactory 

 cells in general appearance, having a rather swollen inner end, containing a 

 comparatively large nucleus. Distally they taper gradually, but appear to 

 end abruptly, while proxinuiUy I believe they are connected with fine nerve- 

 fibres. These cells are invisible in preparations stained by ordinary methods, 

 but stain deeply with the gold chloride, with the exception of their nuclei, 

 while the surrounding tissues remain vaguely defined. Fig. 5 gives a general 

 idea of their appearance, while fig. (j is a drawing of a few of them at a 

 higher magnification, showing how the fine nerve-fibres appear to come 

 into connection with them. These fibres I have been unable to trace through 

 the corium, owing to the dense pigment. On dissolving the pigment by 

 means of Mayer^s chlorine bleaching method, the tissues will no longer 

 stain properly. Hence I can only conjecture (and it seems a reasonable 

 hypothesis) that nerve-fibres pass from the network beneath the corium, 

 through the latter, to reach tiiese fusiform cells in the epidermis. In order 

 to establish the existence of these cells more certainly, I have made prepara- 

 tions of them in glycerine by macerating the tentacles with weak alcohol, 

 and also with osmic acid. I hoped also in this way to be able to see more 

 clearly their connection with the nerves, but in this I was disappointed. 

 Fig. 7 is a composite group of a number of these elongated cells, isolated 

 in this way. This method seems to leave little doubt that such cells actually 

 exist as component parts of the epithelium. They are exceedingly numerous, 

 occurring singly among the ordinary cells of the epidermis, and not forming 

 groups as taste-buds. They only occur near the tips of the fine branches, 

 and not on the main stem of the tentacle. This might, perhaps, account for 

 their having been hitherto overlooked. 



It is interesting to notice, however, that Zincone, in the paper already 

 cited, has given an account and a figure of certain elongated cells, whicLhe calls 

 " cellule fusiformi," in the epidermis of the free fin-rays of Trigla. These 

 cells are connected with nerve-fibres passing through the dermis. He says_, " Lo 

 strato epidermoidale riposa sopra una zona di connettivo omogeneo irto di 

 processi papilliformi. Le cellule fusiformi a due poll fanno continuazione 

 non interotta con le papille, e probabilmente raggiungono la cuticola." His 

 figure shows one of these cells with its nerve, but the " probable " con- 

 nection with the cuticle is only represented by a dotted line. It will readily 

 be seen that these cells have a certain resemblance to the elongated cells in 

 Blennius ; but to what extent they are homologous (or analogous) with them 

 is doubtful. 



Cells somewhat similar in appearance are also described and figured by 

 Morrill [6] from the free fin-rays of Prionotus, another member of the 

 Gurnard family. He appears to have satisfied himself that they are tactile 

 in function, and used in finding food. 



I find fusiform cells also in the nasal tentacles of B. gattorugine, in sections 



