SPIDERS 45 



traversed by the spokes radiating from the centre. The spider 

 does not always work steadily round the frame in the same direc- 

 tion, but may construct spokes alternately to right and left 

 of the first perpendicular. The v/eb is now ready for the lines 

 connecting the spokes. These are arranged in a spiral manner. 

 The spider proceeds to the centre, attaches a thread, turns round, 

 emitting silk all the time from the spinnerets, and with these 

 organs, assisted by the hind-legs, fastens the line to spoke after 

 spoke, travelling farther and farther from the centre until the spiral 

 has attained sufficient size. The intervals between the successive 

 turns of this spiral are relatively wide. A second spiral is now 

 begun, but in the reverse direction from the circumference, 

 inwards towards the middle. If at the margin the spaces between 

 the spokes are too wide for the spider to stretch across, it runs 

 up the spoke to which attachment has been made until, by the 

 convergence, it is possible to step across to the next. Along 

 this it runs outwards to the desired spot, then inwards again 

 along the same spoke, and so on repeatedly until it has reached 

 a region where these laborious to-and-fro journeys and frequent 

 turnings are no longer necessary. As the second spiral is made 

 the first is removed bit by bit, and the second is more closely 

 set, so that its meshes are narrower than those of the first. The 

 writer has observed individuals which did not maintain regularity 

 of direction in tracing the second spiral, but after spinning a 

 few turns in one direction did a few meshes, or perhaps several 

 complete circles, in the other. The central part of the web is 

 usually cut away, so that the spokes do not actually meet at 

 a point, and the space is filled in with irregular meshes of non- 

 adhesive silk upon which the spider frequently rests, head down- 

 wards. The silk used for the spirals is far finer than that of the 

 spokes, and is covered with microscopic globules of sticky 

 material ; whereas the spokes when dry are hardly adhesive. 

 The whole process of constructing a complete web may be com- 

 pleted in half an hour. When at rest the spider keeps each leg 

 in contact with a distinct spoke, and then is able at once to de- 

 tect the vibration caused by the struggles of an entangled insect, 

 and the whereabouts of the victim. If a high-pitched tuning 

 fork be struck and held near the web the spider is deceived into 



