THE DIRECTIVE INFLUENCE OF THE SENSE OF SMELL IN THE 



DOGFISH. 



By G. H. Parker, 

 Professor of Zoology, Harvard University. 



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The object of the professional fisherman is to bring fish within his reach. In some 

 instances this is accomplished by direct attack, as in such primitive operations as har- 

 pooning and spearing, or by circumvention, as in most forms of seining. But in many 

 cases some deceptive device is set up whereby the fish is lured to its fate. These decep- 

 tions are practiced on the fish through some of its various sense organs. Noises are 

 made by the slapping of oars or other such implements on the water and thus fish are 

 driven into gill nets or entangled in trammels. Such influences probably affect the 

 iBsh through the ear, the sense organs of the lateral line system, or the skin, thus involving 

 hearing and touch. Lights are often carried on boats at night and small fish are thus 

 attracted in sufficient numbers to be easily caught by hand nets, a procedure dependent 

 upon the organs of sight. But fishing in the ordinary acceptation of the term implies 

 the use of some deceptive attraction in the form of bait, which, as originally used, 

 depends on the feeding habits of the fish and has to do with its senses of smell and of 

 taste. 



The sense of taste has been almost universally attributed to fish, and most fisher- 

 men, naturalists, and even anatomists have assumed that fishes possessed a sense of 

 smell. Of recent years some comparative physiologists have denied this sense to 

 fishes. In their opinion the nasal organ of the fish acts more as an organ of taste 

 than an organ of smell. This conclusion was thrown in question by the observations 

 of Aronsohn (1884) and of Baglioni (1909), and was refuted by the experiments of 

 Parker (1910, 191 1), Sheldon (1911), and Copeland (1912). By these studies it was 

 shown that fishes scent their food in essentially the same manner that air-inhabiting 

 vertebrates do and with the corresponding sense organ, the nasal organ. 



The following investigation has been carried out with the view of -.scertaining 

 the exact method by which a fish finds its food or may be caught by a bait. The work 

 has been done on the smooth dogfish of the Woods Hole region, Mustelus canis (Mitchell). 

 The gustatory, chemical, and olfactory senses of this fish have already been studied by 

 Sheldon (1909, 191 1), and it was therefore an unusually favorable subject for the investi- 

 gation of those activities which depend upon the sense organs named. 



The experiments were carried out for the most part in a small pen, 24 feet long by 

 6 feet wide, in one of the pools of the Woods Hole station. The pen was bounded partly 



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