150 PHYSIOLOGY CHAP. 



the electrodes being at a certain distance from each other, and on 

 then breaking the current, the original acid taste at the anode 

 became first slightly bitter and then alkaline, while the alkaline 

 taste at the kathode simultaneously became acid. 



These observations were repeated and confirmed with variations 

 by Hermann and Laserstein (1891), Shore (1892), and Hofmann 

 and Bunzel (1897). Hermann and Laserstein showed that it is 

 not the oscillations in the intensity of a constant current but the 

 current itself which produces the electrical taste. The com- 

 paratively weak effect of induced currents is due to their brief 

 duration. On applying the anode to the tongue there is a 

 decidedly acid taste during the passage of the current ; on apply- 

 ing the kathode the taste becomes alkaline. But the acid taste 

 is more pronounced than the alkaline, and is not neutralised by 

 alkaline fluids. On breaking a weak galvanic current there is an 

 acid after-taste even when the taste has been only slightly alkaline 

 during its passage. Shore obtained similar results. 



Hofmann and Bunzel stated that when the kathode is applied 

 to the tongue there is a burning sensation during the passage 

 of the current, accompanied by a bitter taste ; on opening the 

 circuit there is a faint acido-metallic taste, which is stronger in 

 proportion as the current had lasted longer. 



According to these authors the primary taste is due to 

 electrolysis, and the acid after-taste at the kathode is a contrast 

 effect, comparable to the phenomena of the same order observed 

 in the visual organs. 



Certain of von Zeyneck's results (1898) also tend to show that 

 sensations of taste produced by electrical currents are the effects 

 of electrolytic dissociation either of the superficial fluids of the 

 mouth or of the fluids that irrigate the cells of the taste buds. 

 He believed, on the strength of exact electrical measurements, 

 that on first passing a minimal ineffective current through the 

 tongue, and then gradually increasing its potential, the anodic 

 and kathodic sensations of taste appear with the intensity of 

 current that produces electrolytic dissociation. 



VII. It seems not improbable that there may be cases of 

 complete congenital absence of the sense of taste, such as are 

 known for the other special senses. A priest known to us in 

 our native town declared that he had been unable from birth to 

 distinguish the different flavours in his food, so that the choicest 

 dish or the coarsest food, coffee with or without sugar, quinine or 

 salt, wine or vinegar, were to him alike indifferent. Unfortunately, 

 he died before we had the opportunity of testing by exact 

 scientific methods his ability to taste (and smell), which might 

 then have been controlled by post-mortem examination. Up to 

 the present no clinical case has been recorded to confirm physio- 

 logical inductions as to the specific nerves of taste and their 



