128 ARACHNIDA. 



the nature of the disturbance which is taking place in its 

 web. In the work above alluded to, it is stated, " We have 

 tried numerous experiments, by moving and vibrating the 

 lines of the webs of many species, so as to imitate, as nearly 

 as possible, the entrapment, of a fly, but in no case have we 

 succeeded in bringing the spider to the spot, because, as we 

 inferred, her eyes always detected our attempted decep- 

 tion." Now the experiments which I have made have 

 produced a result so contrary to the above, that it is not 

 without a repetition of them that I have ventured to adduce 

 them against the statements in question. These experiments 

 were chiefly made upon the Epeira diadema, one of the 

 largest of the British species, which, from its very common 

 occurrence, beautiful markings, and elegantly-constructed 

 web, must have attracted the attention of the most casual 

 observer in the autumn. Now from its size it is evident, 

 that, if the intelligence which these insects obtain respecting 

 the entrapment of a fly results from the sense of sight, the 

 epeira would make no use of its legs for obtaining such 

 knowledge, and that its eyes alone would be brought into 

 action ; but so far is this from being the case, that I have 

 repeatedly disturbed the lines of the web within an inch of 

 the spider, and in the direction of its eyes, but in every in- 

 stance the legs have been instantly put in motion, which has. 

 been continued for a considerable time even after. I have 

 ceased the disturbance in order that, if possible, the spider, 

 by slightly moving the web itself, might set the fly, which it 

 evidently supposed to have been captured, in motion again, 

 so that, by its repeated struggles, it might ultimately fall an 

 easier prey to the inhabitant of the web. But in addition to 

 this fact, it is to be observed, that the den-like retreats of 

 many spiders are so placed that they cannot possilily see 

 any thing which occurs on the web, and yet no sooner is a 

 fly entrapped in any part of the web than the spider instan- 

 taneously acquires a knowledge of the fact, evidently hy 



