CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE MUSEUM OF COMPAR- 

 ATIVE ZOOLOGY AT HARVARD COLLEGE, UNDER THE DIRECTION OF E. L. MARK, 

 Director. No. 2og. 



OLFACTORY REACTIONS IN FISHES 



G. H. PARKER 



The fact that the olfactory apparatus, both peripheral and 

 central, is very well developed in most fishes has led many mor- 

 phologists to ascribe to these animals a keen sense of smell; but 

 this opinion has been unsupported by physiological evidence, for 

 up to the present tmie investigators of the subject have not been 

 able to demonstrate any form of stimulation or reaction charac- 

 teristic of this apparatus in water-inhabiting vertebrates. The 

 observations of Aronsohn ('84, p. 164), that a goldfish, which 

 ordinarily will eat ant pupae with avidity, will not take these 

 pupae after they have been smeared with a little oil of cloves, 

 are not conclusive evidence that the fish scents the oil, for it is 

 entirely possible that this oil merely irritates the skin of the fish's 

 snout and does not stimulate the olfactory apparatus at all. Nor 

 is the discovery made by Steiner ('88, p. 47), that the spontaneous 

 appropriation of food by Scyllium ceases on the removal of the 

 cerebral lobes or simply on cutting the connections between these 

 lobes and the olfactory bulbs, satisfactory evidence that the olfac- 

 tory apparatus in these fishes is an organ of smell rather than a 

 receptor for taste or soiil'e closely allied sense. Nagel ('94, p. 184) 

 noted that the front portion of the head of Barbus was as sensi- 

 tive to sapid substances after the olfactory tracts had been cut 

 as before that operation, and Sheldon ('09, p. 291), who has stud- 

 ied the dogfish with great fulness, demonstrated that the decided 

 sensitiveness of the nostrils of this fish to weak solutions of oil 

 of cloves, pennyroyal, thyme, etc., was not influenced by severing 

 the olfactory crura, but disappeared on cutting the combined 

 maxillary and mandibular branches of the trigeminal nerve. 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 8, NO. 4. 



