Art. VI] Herrick, Tustc in Fishes. 47 



Silurus glanis. (Merkel, '80). 



Solea vulgaris, sole. "Contrary to the natural presumption, 

 the villi on the lower (left) side of the head do not bear 

 sense organs, though, as Mr. Cunningham informs me, 

 such organs are found between the villi" (Bateson, '90). 

 Tincta vulgaris. On barblet (Merkel, '80). 



As already suggested, our knowledge of the functions of 

 all of the sense organs of fishes is very imperfect, since specula- 

 tion based upon structure has seemed more attractive to most 

 authors than accurate physiological research. The monograph 

 of Merkel ('80) with its great wealth of accurate anatomical 

 data on the structure and distribution of terminal buds in all 

 classes of vertebrates, gives an excellent illustration of the dan- 

 gers in the path of even so skillful an observer when he goes 

 beyond the bounds of observed fact and enters the field of 

 speculation. This author recognizes the close structural resem- 

 blance between these organs and the undoubted organs of taste 

 in the human body. He controverts, however, the clear argu- 

 ment of F. E. Schulze for their gustatory function on merely 

 theoretical grounds. His first objection is based on their inner- 

 vation. Instead of being supplied by a single gustatory nerve, 

 the glossopharyngeus, they may be supplied, he says, by any 

 other body nerve. This objection has been totally removed by 

 the discovery (compare especially my own Ameiurus paper, 

 already referred to, published in October, 190 1) that all terminal 

 buds, no matter where located on the body and no matter from 

 what nerve branches their innervation seems to come, are in 

 reality supplied by nerves of a single physiological system, ter- 

 minating in the brain in a single center — the communis nerves. 

 Again, he objects to Schulze's theory that the terminal 

 buds serve to localize gustatory stimuli on the various parts of 

 the body, on the ground that an organ of chemical sense stim- 

 ulated by substances in solution in the environing fluid could 

 not receive a sufficiently circumscribed stimulation. It is un- 

 necessary to follow the argument in detail, for the experiments 

 which I shall describe shortly show conclusively that when the 

 sapid substance is brought into contact with these organs or very 



