HAVE FISHES MEMORY. 391 



monids typify the two extremes well. The degree of hung-er felt 

 impedes or facilitates, as the case may be, .the production of the series 

 of reflexes. It can be imagined, too, that certain acute irritations, 

 such as from wounds, etc., exert a restraining influence with regard 

 to the taking of food. Furthermore, every angler knows the eft'ect of 

 changes in temperature and weather upon flshes in their relation to 

 food. About thirty correspondents tell me of flsh of prey which still 

 carried the hook they had torn from the line in their mouth, and per- 

 mitted themselves to be caught with another immediately upon their 

 escape or after an interval. Such cases do not prove, as my inform- 

 ants think, that these flsh have no memory. They are as little al^le to 

 judge by the appearance of the second bait as they had been by that of 

 the flrst that a hook was concealed in it. The same trick ma}' deceive 

 even human beings several times. Moreover, we do not know whether 

 fish feel pain when the sides of their mouth cavity are pierced. Indeed, 

 a number of facts make it seem doubtful whether what human beings 

 designate as pain extends very far down into the lower order of ani- 

 mals. Fish of prey, endowed with a keen desire for food at all times, 

 suffer enormous injuries without suffering corresponding impairment 

 of appetite. Duim (Contemporary Review, 1899) reports that a shark, 

 which was caught with the hook, and was opened in order to remove 

 the liver for medical purposes, and was then returned to the water 

 half dead, soon after was caught again with bait. He also saw a 

 Motella caught with the hook whose stomach was pulled out so far 

 that it hung from under the gill bars. He supposed that the flsh had 

 suffered this serious injury fron\ the hook of an earlier angler from 

 whom it had escaped. In the supplement to the Allgemeine Zeitung, 

 1897, No. 213, E. St., in an article describing his journeys in the 

 South Pacific, relates that sharks which have slipped from a fisher- 

 man's hook, and in doing so have torn their upper jaw, almost alwa3'^s 

 rise to and swallow the same bait. In the stomach of one shark he 

 found, besides the claw of a crab deeply embedded, a piece of cor- 

 roded iron, which, after piercing the walls of the esophagus with its 

 pointed end. had inflicted an injury upon the pericardium, the scar of 

 which still .showed. On closer examination the iron turned out to })e 

 an old shark hook of very nearly the same kind as the one with which 

 the fish was eventually caught. 



The same disposition has been noticed in Emx. Fifteen or twenty 

 minutes after it has been grappled it allows itself to be caught with 

 the same hook. 



The avidity with which hungry fish rise to bait varies in closely 

 related species. Salmo salvelinus [the charr] and Sahno iridea [rain- 

 bow trout] occasionally snap at a moving finger, Salmo fario [the 

 European trout] never. 



Many fishermen insist that fish " know" the hook. To me it seems 



