SPIDERS. 355 



thin filaments from each spinneret unite into a thread, and the thread 

 of one spinneret is often combined with that from the others. In this 

 way a compound thread of exquisite fineness, though rivalled by a 

 quartz-fibre, is produced ; but two or four separate threads are often 

 exuded at the same time. Before beginning to "spin," the spider 

 often presses the spinnerets against the surface to which the thread is 

 to adhere, and draws the filaments out by slowly moving away. Often, 

 however, the filaments ooze out quite apart from any attachment. The 

 legs are also much used in extending and guiding the thread, and some 

 spiders have, as has been mentioned, a special comb (calamistrum). 



One of the most important ways in which the secreted threads are 

 used is in forming a web. The common garden spider (Epeira) makes 

 a web which is a beautiful work of unconscious art, and very effective 

 as a snare for insects. The spider first forms "foundation lines" 

 around the selected area ; it then swings across the area with the first 

 i: ray," which it fixes firmly ; another and another is formed, all inter- 

 secting in one centre. Thirdly, it starts from the centre, and moves 

 from ray to ray in a long wide spiral gradually outwards, leaving a 

 strong spiral thread as it goes. Fourthly, the spider moves in a closer 

 spiral from the circumference inwards, biting away the former spiral, 

 replacing it by another, which is viscid and adhesive. It is to this that 

 the web chiefly owes its power of catching insects which light there. 

 There is usually a special thread running to the adjacent hole or nest, 

 and the spider feels rather than sees when a victim is caught. 



The spun threads are used in many other ways. They line the nest, 

 and form cocoons for the eggs. They often trail behind the spiders as 

 they creep ; they greatly assist locomotion, and are used in marvellous 

 feats of climbing. Small and young spiders often stand on tip-toe on 

 the top of a fence, secrete a parachute of threads, and allow them- 

 selves to be borne by the wind. The fallen threads are known as 



gossamer. 



Courtship. The males are usually much smaller than the females. 

 It is calculated that the disproportion is sometimes such as would be 

 observed if a man 6 ft. high and 150 Ib. in weight were to marry a 

 giantess of 76-90 ft. high, 200,000 Ib. in weight. It may be that the 

 smallness of the males is mainly due to the fact that they are males ; 

 others explain it by saying that the smaller the males are, the less likely 

 they are to be caught by their frequently ferocious mates. 



The males are often more brilliantly coloured than the females, 

 perhaps, again, because they are males, though what the physiological 

 connection between the male constitution and bright colours is in this 

 case we cannot tell till the nature of the pigments is known. Wallace 

 has spoken of the frequent brilliancy of males as due to their greater 

 vitality, and refers the relative plainness common in females to their 

 greater need for protection. Darwin referred the greater decorativeness 

 of males to the fact that those which varied in this direction found 

 favour in the eyes of their mates, were consequently more successful 

 in reproduction, and thus tended to entail brilliancy on their male 

 successors. The careful researches of Prof, and Mrs. Peckham greatly 

 strengthen the position of those who believe in the efficacy of sexual 

 selection. In the "Evolution of Sex,"' it has been suggested that 



