436 JOHN B. WATSON 



to improve in estimating the depth of objects. The author makes 

 no mention of the influence of the vibrissae in the last two tests, 

 yet he speaks of the marked " stereotactic " instinct. One of 

 the most obvious things to do in making such tests upon an ani- 

 mal which uses its vibrissae to such an extent as the mouse is 

 to keep them clipped from birth. Not until then can one force 

 the animal to show clearly what powers of accommodation and 

 convergence it has. The author's findings on the anatomical 

 side are in agreement with those obtained several years ago by 

 Slonaker. The retinae of the mice are lacking largely in cones. 

 There is no fovea. The range of vision is wide, and there is 

 the possibility of a small binocular field. 



AUDITION 



Fish. — Bernoulli ^"^ gives a clear and succinct account of the 

 work done on hearing in fishes. His own results support the 

 negative conclusions of Kreidl and of Korner, and are against 

 the positive conclusions of Zenneck and of Parker. He repeated 

 the experiments of Zenneck, but worked more carefully than 

 the latter. A bell with C3 for its fundamental, with a basal 

 diameter of 94 mm. and height of 62 mm., was fastened to a 

 very firm support with the dome immersed in water (" mit 

 der Kuppel nach unten eingetauscht "). The bell was electro- 

 ma-gnetically actuated. The key for closing the circuit was 

 placed several meters away, behind a stone wall. The fish 

 (" Forellen," also eels and individuals belonging to Zander, 

 Lucio perca sandra, cuv.) were tested in an open stream, and 

 hence under natural conditions of life. He was not able to get 

 the slightest reactions under these conditions. " In keinem 

 einzigen Fall haben die Forellen {Salmo fario L.) irgendwie 

 auf das Lauten der Glocke reagiert." 



Incidental observations showed that the fish (Salmo fario L. 

 and Thyniallus vulgaris Nilos) were totally insensitive to shrill 

 pipes, the sound weaves from which were conducted to the water 

 by the aid of a metal tube 4 m. long and 30 mm. in diameter. 

 Other observations showed that the fish (Zander?) were totally 

 insensitive to pistol shots fired at a distance of 2 km. His final 

 conclusion is that the fish do not hear, but respond tactually 

 or visually, when at all, to the mechanical motion in the water. 



