442 AMERICAN SPIDKKS AND THEIR SPINNINGWOKK. 



its way home after the danger is over. There would thus be a double 

 advantage in absolute quiet. ^ It will be remembered that as a spider 

 drops from a web or other roosting place it spins a line, which forms a 

 straiglit path backward from the starting point to the stopi)iiig 

 Origin of point It can thus easily return to its snare or roost by means 

 _,®f' . of this traphne, provided it remains quiet at the first point of 

 ' stoppage. But, if the spider moves, its trapline becomes a drag- 

 line, the end of which adheres to the first point of stoppage ; after another 

 short interval this is attached to another point, and so on, to another 

 and another as the spider moves. 



Now, the Peckhams think that tins last action tends to confuse a spi- 

 der, and make its path homeward indirect. In this view they seem to 

 think themselves justified by some experiments made with the Labyrinth 

 spider, and to some extent I have no doubt they are correct. But I hardly 

 agree with them in the importance which they give to this fact as em- 

 phasizing the theory that it would be of great value to the spider to re- 

 main quiet at the point first reached after dropping from its web. It 

 seems to me that it is not difficult for a spider to return by its dragline 

 to the point where it might reach its dropline, unless, indeed, it should 

 wander far into the mazes of leaves, or by any mi,sfortune its dragline 

 should be broken and thus lose its trail. The truth or falsity of this 

 view is interesting, because of the opinion of the Peckhams that tlie pos- 

 sibility of losing itself makes it much more to the interest of the spider 

 to remain quiet at the place it first reached when dropping from its snare ; 

 and, further, that this usefulness of the quiet attitude may have been the 

 starting point from wliich, by natural selection or otherwise, the death 

 feigning liabit may have been developed. 



The matter seems to me to require further test before one can posi- 

 tively decide. At all events, tlie Peckhams accept Darwin's explanation 

 of the habit of lying motionless as the result of natural selection, and 

 that it has been acquired by different species in different degrees accord- 

 ing to its usefulness in their various modes of life. Thus we find it in its 

 greatest development among the comparatively sluggisli Epeirids, whereas 

 it is badly developed or lacking in the running or jumping spiders whicli 

 are able, as any one who has pursued them will testify, to move with as- 

 tonishing raj)idity.^ 



In connection with this subject the question naturally arises as to 

 whether insects show any sign of fear in the presence of spiders. Camp- 

 bell only once observed an attitude in a fly which might be taken 

 Fearless ... 



Plies '^^ coincident with fright paralysis. The fly was about one and 



a half inch from Tegcnaria domestica, was busy cleaning itself, 

 when suddenly it stood motionless in the very act of rubbing its claws 



' Op. fit., page 413. ' Ibid., page 417. 



