g6 B^dlctin of Laboratories of Denison University. [Voi. xii 



senses of smell and taste, and I have not as yet gone far enough 

 with this series of experiments to decide finally the part played 

 by smell. 



I have, however, tested the sensitiveness of the barblets to 

 diffused savors more fully. Raw meat or beef liver was minced, 

 extracted in a little water and strained. A wisp of cotton was 

 wound on the end of a slender wire, dipped in the meat juice 

 and gently lowered so as to lie a few millimeters from the tip of 

 a barblet of a cat fish which was otherwise entirely concealed 

 under a large leaf. The fish was unable to see the cotton and 

 actual contact with the barblet was carefully avoided. Within 

 a few seconds the fish becomes conscious of the savor and turns 

 totvard the cotton. Again, I filled a glass tube of about 3 mm. 

 bore with meat juice, closed the upper end with the finger and 

 carefully lowered the open end down over a projecting barblet, 

 as in the previous case. The specific gravity of the meat juice 

 is slightly greater than that of the water and from the lower 

 end of the tube (the upper end being kept closed) the juice slowly 

 diffuses downward enveloping the tip of the barblet, without, 

 however, any noticeable current being produced in the water. 

 The fish locates the stimulus and turns towards the source of it. 

 In other cases I colored the juice with a little blood, so that 

 the course of the diffusion currents could be observed, and it is 

 evident that the reaction follows the stimulus of the barblet ox\\y , 

 and not the organ of smell, for the movement is made before 

 the diffusion currents have had time to reach the nostril. 



These reactions are not as prompt or precise as those given 

 after contact with a sapid substance where a tactile sensation ac- 

 companies the gustatory, and in a large percentage of the cases 

 there is no definite reaction toward the point stimulated but 

 merely the more vague "seeking reaction" to which reference 

 has been made above. Nevertheless they indicate on the 

 whole that pure gustatory stimuli, if very strong and applied to 

 a small area of the percipient organ, can be localized tn space, or 

 have a ''local sign." 



May JO, 190J. 



