TENTACLES OF BLENNIUS GATTORUGINE. 303 



As a further test, three specimens were etherized, and in two of them the 

 optic nerve on either side, and the olfactory tracts, were cut. In the third 

 the olfactory tracts only were severed. These specimens still reacted to 

 chemical ao-onfcs, such as acetic acid, as might be expected, but this fact is of 

 no value. Their tentacles were very sensitive to touch, especially in those 

 whose optic nerves had been cut. After a rest of some four days, to allow 

 of recovery from the effects of the operation, the three fishes were placed in 

 a small aquarium and tested with worms and pieces of worms. The two 

 which had been blinded showed no sign of noticing the food when placed on 

 the bottom of the vessel near their snouts or eyes. The unblinded specimen 

 shelved signs, as might he expected, of perceiving them by sight. When 

 pieces were lightly brushed against their tentacles, all three specimens at 

 first backed away, as if reacting to an ordinary touch-stimulus. One of the 

 blinded individuals, however, appeared to recognize the presence of food. 

 He made a feeble snap at it, but did not swallow it. In fact, none of them 

 fed at all. After two or three trials they ceased to react at all to the stimulus 

 of touch applied to the tentacles. As a control, three normal specimens were 

 fed in the same vessel, two of which fed readily. On the two following days 

 the same procedur(i was gone tlirough, with similar results. I am inclined 

 to believe that in the one fish wliicli seemed to recognize food the olfactory 

 function may not have been completely destroyed. 



The only conclusions with regard to the tentacles which it is possible to 

 deduce from the above meagre evidence are : — 



(1) That the tentacles are very sensitive to toucli. 



(2) That they may recognize the " feeP' (? the taste or odour) of the 



substance that touches them. This, however, is verv doubtful. 



As to the normal function of the tentacles, therefore, I am still undecided. 

 The only tact which seems tolerably certain is that they contain some nervous 

 apparatus wliich is eminently sensitive to touch, whether the stimulus comes 

 from an article of food or an inanimate object. Thus, normal specimens 

 whose tentacles are lightly touched with a glass rod as they lie on the 

 bottom of an aquarium, will lean over in an ahnost ludicrous manner away 

 from the side touched, at the same time moving their eyes to see the source 

 of irritation. Whether my fusiform cells play any part in the perception of 

 this kind of stimulus is a question which I must leave unanswered. 



It would have been interesting if it could have been shown that the 

 tentacles were sensitive to disturbances or vibrations in the water, due to the 

 movements of other animals or to deliberate stirring by artificial means. 

 From the habit shown by these fishes of lying half concealed among rocks 

 and stones, often with only the head exposed and the tentacles erect, this 

 would almost seem a likely function. I have not, however, been able to find 



