Image d'archive à partir de la page 318 de l'American spiders et leur rotation. American spiders et leur travail de bobinage. Une histoire naturelle de l'orbweaving spiders des États-Unis, avec une attention particulière à leurs habitudes et de l'industrie Année : 1889 CUbiodiversity1121211-9810 ( LES SENS ET LEURS ORGANES. 311 mais pense que les fonctions de ces trois types ne sont pas identiques, puisque être trouvés sur le même individu, on ne peut plus admettre que trois différents organes sont construits pour le même rôle physiologique. Pourraient-ils assumer différents degrés de la même fonction ? Wagner docs n
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Archive image from page 318 of American spiders and their spinning. American spiders and their spinning work. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits CUbiodiversity1121211-9810 Year: 1889 ( THE SENSES AND THEIR ORGANS. 311 but thinks that the functions of these three types are not identical, since being found upon the same individual, one cannot well admit that three different organs are constructed for the same physiological role. Might they not, however, serve for different degrees of the same function? Wagner docs not doubt that spiders have a delicate sense of hearing, but the objective ground on which he rests it is unreliable. He states it as 'a fact known to all biologists, ' that in order to entice a spider from its nest or den it is only necessary to cause a fly to buzz near it, while an unskillful imitation of the buzzing sound fails to deceive the ara- nead. On the contrary, even the pres- ence of flies in the web often fails to tempt the spider forth; and I know that unskillful imitations of insects have often drawn them forth; but such imi- tations I have never conffned to sounds. They are only or chiefly successful when the movement is communicated to the threads of the web itself. AVagner admits that if the movement of hairs of any type under the influence of sound could be proved, that would suffice to assign to that type the role of an auxiliary auditory organ, at least. But, in fact, it is far from being proved tliat sound sets the so called auditory hairs into movement. At least his own experiments failed to show this. By the aid of an electric lantern he was able to throw distinctly upon a screen figures of a row of auditory hairs, enlarged to the size of from three to six inches. He had prepared a fine section of that portion of the foot which is provided with auditory hairs, and this had been so placed as to allow free movement. Sounds of various sorts and tones were the
