THE INSTINCT OF SPIDERS 145 



The spider then climbs away along the new filaments 

 and escapes. 



The principle of protective resemblance is evident 

 in the behaviour of these spiders. The Tetragnatha, 

 when alarmed, remains perfectly motionless and thrusts 

 forward the front two pairs of limbs, the tips of which 

 diverge slightly from one another. This attitude is, 

 I imagine, of some importance to the spider, for it no 

 longer bears any resemblance to a living creature, but 

 might be easily confused with the flowers of the 

 grasses that on all sides surround the snare, and to 

 which the structure is often attached. 



But there is in these hills another geometrical spider, 

 unnamed, but belonging to the genus Cyclosa, which 

 adopts a still more perfect method of protective 

 resemblance. It envelops its captured flies in a coat 

 of silk so as to form little pellets which it strings along 

 one of the diameters of the snare, almost always, I 

 think, in the vertical direction. The spider itself very 

 closely resembles one of these silken pellets. It is of 

 a brownish-white colour, and, when it tucks in its legs 

 and remains motionless, it is not easy to tell which is 

 the spider and which the pellet. The general shade 

 of colour varies in different individuals. Some speci- 

 mens, or it may be species, are distinctly browner 

 than others, and the little pellets which they construct 

 are correspondingly of a darker hue. But in addition 

 to the close resemblance, the spider's position in the 

 snare must be of great value, for it sits at the centre 

 in the direct line of the row of pellets which are strung 

 along the diameter on either side. So perfect is the 

 resemblance that it is almost impossible to detect the 

 presence of the spider unless it is remembered that it 



