302 MR. H. A. BAYLIS ON THE 



In most particulars the " Kolben," if I may so call them, of the tentacles 

 o£ Blennius agree closely with those o£ Petromyzon ; but they nearly always 

 appear to have an opening on the exterior between the outer layer of 

 epidermal cells. I have not observed cross-striations or fat-globules in thenij 

 but the double nucleus and the clear cavity are almost always visible. The 

 latter, however, is always open and of a cup-like shape. The "Kolben" 

 usually either touch the cutis at their lower ends, or are only separated from 

 it by protoplasmic processes from the surrounding cells, rarely by any 

 complete cells with nuclei. (Of course, an appearance of this kind may be 

 produced in sections whicli do not pass quite through the longitudinal axis 

 of the "Kolben.'^) I have not been able to discover any nerve-fibres in 

 connection with them, and do not think that they ever form any connection 

 with my vertical connective-tissue " blocks.''' 



As regards the function of the tentacles, and especially of the peculiar cells 

 previously described, which seem to me to be undoubtedly sensory, I am not 

 in a position to make any definite statement. Ajiart I'rom inor[)hological 

 considerations, whicli would lead one to suppose that these cells might be 

 olfactory in function, the only means of investigating this question is the 

 experimental method. There are, however, great difficulties in the way of 

 reaching any certain conclusions by this means. Thus, even if one could 

 prove that thc^ tlsh recognized the presence of food or of chemical substances 

 by the use of their tentacles, by cutting off all other avenues of perception, it 

 would be well-nigh impossible to say whether the sensation appreciated was 

 one of smell, of taste, or of what G. H. Parker, in a recent paper, has termed 

 the "common chemical sense." The few experiments which I have made in 

 this direction are not of much value for this reason. I tested a few normal 

 specimens first with certain reagents, with a view to finding out whether the, 

 tentacles were sensitive to them. In each case a small pellet of wool was 

 dipped in the reagent, and then (first) held over or near the tentacles in the 

 water, and (secondly) lightly brushed against them. To oil of cloves there 

 was no perceptible reaction. Acetic acid caused a ra])id retreat on the part 

 of the fish ; they backed away as soon as the diffusing acid reached them, and 

 without being touched by the pellet. But the movements of the mouth and 

 opercula showed that some of the acid had got into the mouth. Hydrochloric 

 acid produced similar results. C-austic soda seemed to have a decided effect 

 when placed near the tentacles, the fish darting away at once. When some 

 of the white precipitate formed entered the mouth, the fish backed a little 

 and spat it out, but did not dart away. Caustic ammonia did not produce 

 any marked effect when presented to the tentacles, but the fish did not seem 

 to like it when presented in front of their snouts. Now it cannot be shown 

 from these experiments that the reactions may not have been due to the 

 stimulation of the free nerve-endings in the skin of the head, or of taste-buds 

 situated either in the mouth or elsewhere. There is no proof that any of the 

 reactions were due to the stimulation of organs in the tentacles alone. 



