No. 2.] MENTAL POWERS OF SPIDERS. 403 



COLOR-SENSE. 



Spiders are often so brilliantly colored that their being en- 

 dowed with a well-developed color-sense seems ^ priori prob- 

 able. Hoping to decide this question, which, as yet, had not 

 been attempted, we began a series of experiments in the summer 

 of 1886. The details of our method we omit, since the results 

 were entirely unsatisfactory. In the following summer, how- 

 ever, we hit upon a plan of procedure which gave us the desired 

 data.^ 



We had worked, during the first year, on species that are 

 found in exposed places, or even in direct sunlight; but in our 



tain leaping gait. The moment, however, it has discovered a fly, all its motions are 

 altered; its cephalothorax, if the fly moves, turns to it, with the firm glance of an 

 animal which can turn its head; it follows all the motions of its prey with the watch- 

 fulness of the falcon, hurrying its steps or slackening its pace, as the case may re- 

 quire. Gradually, as it draws near to the unsuspecting victim, its motions become 

 more composed, until, when very near, its movements are entirely imperceptible to 

 the closest observation, and, indeed, it would appear perfectly motionless, were it not 

 for the fact that it gradually draws nearer to the insect. When sufficiently near, it 

 very suddenly takes a leap, very seldom missing its aim. I saw one, however, make 

 a mistake, for the object which it watched was only a portion of the wing of an 

 hemipterous insect entangled in a loose web. It took its leap and grasped the wing, 

 but relinqviished it immediately, apparently very much ashamed of having made such 

 a blunder. This proves that the sight of spiders, though acute, is not unerring." 

 — Spiders of the United States, p. 56. 



Also, Bingley says of the jumping-spider : "If it sees a fly at the distance of 

 three or four yards, it does not run directly to it, but endeavors, as much as possible, 

 to conceal itself till it can arrive near; and then creeping slowly up, and but seldom 

 missing its aim, it springs upon the insect's back, and it is then almost impossible for 

 the fly to effect an escape. But if, before the spider gets to it, the fly takes wing, 

 and fixes upon another place, it whirls nimbly about, and still keeps its eyes upon it, 

 in order to commence a fresh attack." — Animal Biography, Vol. III., p. 455. 



While it is probably an exaggeration to speak of a spider seeing an object at a 

 distance of three or four yards, it would scarcely have been possible for the writer to 

 make such a statement if the spider he had been watching had been able to see only 

 at a distance of three or four inches. 



• Mr. Wallace, in Tropical Nature, p. 238, remarks that " the fact that the 

 higher vertebrates, and even some insects, distinguish what are to us diversities of 

 color by no means proves that their sensations of color bear any resemblance what- 

 ever to ours. An insect's capacity to distinguish red from blue may be (and prob- 

 ably is) due to perceptions of a totally distinct nature." 



It is true enough that the mental states of men and insects must differ greatly, but 

 if we are to comprehend the sensations of insects at all, we must do so by thinking 

 of them in terms of the only conscious states that we know anything about, namely, 

 our own. For this reason we shall assume that when a spider distinguishes red from 

 blue, the best conception of its feelings will be attained by reference to our own 

 sensations under similar circumstances. 



