42 Bulletin of Laboratories of Denison University [voi. xii 



problem of vertebrate anatomy. And in this I have not been 

 disappointed, though my study of the central paths is not yet 

 sufficiently advanced for publication. 



As intimated above, sense organs belonging to the com- 

 munis system and presumably serving the function of taste are 

 found in the mouth of all fishes ("taste buds"). They are fre- 

 quently found upon the lips, and in some cases they are found 

 likewise plentifully distributed over extensive areas of the outer 

 skin of the head and trunk. In this latter case they are com- 

 monly termed terminal buds or end-buds {Endknospen, Becheror- 

 gane, of the Germans). They must in all cases be sharply dis- 

 tinguished from the neuromasts, or organs of the lateral line 

 system (German, Nervenhugel), though these latter occur in the 

 skin of fishes in a great variety of forms, often resembling the 

 terminal buds very closely. The innervation and functions of 

 the two systems of organs are, however, wholly different, and 

 they really have nothing to do with each other. I shall illus- 

 trate more fully in a later section of this paper the structure of 

 the terminal buds and the details of their innervation; I here call 

 attention merely to the important fact that both in structure and 

 in nerve supply they resemble most closely the taste buds of the 

 mouth. From this one naturally infers for them a gustatory 

 function. Since, however, inferences are not in order when 

 facts are available, I have undertaken to determine experimen- 

 tally the function of these cutaneous sense organs of the com- 

 munis system. 



The experiments which I have made are of an exceedingly 

 simple nature, the attempt being to put the fish while under ob- 

 servation in as nearly normal conditions as possible and to util- 

 ize the ordinary feeding and other instinctive reactions so far as 

 possible in the accumulation of the data. These are the meth- 

 ods of the old-time observational natural history, it is true, as 

 contrasted with the methods of precision of the modern physio- 

 logical laboratory. They have, however, proven sufficient for 

 their purpose, which was merely to determine the class of stimuli 

 to which the terminal buds are sensitive, or the sensational 



