48 Bulletin of Laboratories of Denison University. [Voi. xii 



near to them, the stimulus is accurately and very promptly 

 localized, and in fact some of the flshes studied habitually find 

 their food by this very power, the gustatory stimulus calling 

 forth an immediate reflex movement toward the point stimula- 

 ted. It is probable that the local sign is not given by the gus- 

 tatory (communis) nerves, but by the accompanying tactile 

 (general cutaneous) nerves of the corresponding cutaneous area 

 (which general cutaneous nerves Merkel curiously enough de- 

 nies to the fishes altogether, whereas in fact they are plentifully 

 supplied to all parts of the skin), though my experiments do 

 not decisively answer this question. Weak stimuli, especially 

 when uniformly diffused through the water are, it is true, not 

 at all localized; but strong stimuli are unquestionably localized 

 by one method or another. 



In fact, Merkel agrees with Jobert that the terminal buds 

 of the outer skin are tactile in function. This is based largely 

 on the erroneous belief, referred to above, that there are no 

 free tactile nerve endings in the skin of fishes, and also on the 

 observed tactile sensibility of the barblets and other parts of 

 the body known to be most plentifully supplied with terminal 

 buds. But I have shown that all of these parts of the body re- 

 ceive, in addition to communis nerves for the specialized sense 

 organs, a most liberal cutaneous innervation for tactile sensi- 

 bility; and the experiments which follow go to show practically 

 that these two functions commonly co-operate in setting off the 

 reflex of seizing food, though they may be experimentally 

 isolated. 



Merkel now proceeds to carry his argument to its logical 

 conclusion (and likewise to a reductio ad absurdum) by denying 

 the gustatory function to all terminal buds, even those within 

 the mouth supplied by the glossopharyngeal nerve, of all verte- 

 brates below the Mammalia. 



He finally concludes that both the neuromasts of the lat- 

 eral line system and the terminal buds are tactile organs, the 

 buds being the more delicate, but, if these are deficient, then 

 the neuromasts may be elevated to a more delicate functional 

 value; both of which conclusions, in the light of our present 



