300 HOMES WITHOUT HANDS. 



It may perhaps be necessaiy to remark that the threads with 

 which the spiders make their webs are in some respects similar 

 to those which are produced by various caterpillars, and in other 

 respects are exceedingly dissimilar. In both cases, the threads 

 are formed from a semi-liquid secretion, which is produced in the 

 internal organs, is forced through minute apertures at the will of 

 the animal, and hardens into a thread as soon as it comes iu 

 contact with the air. 



Here, however, the resemblance ceases. The threads of the 

 caterpillar are double, or rather are composed of two lines fused 

 together throughout their length, the two half-lines proceeding 

 from a large silk-secreting tube at either side of the body, and 

 iiniting at the mouth, where they become fused together by 

 passing through a short tube common to both. The threads of 

 the spider are much more complex, each being formed of a vast 

 number of smaller lines, which are produced from a peculiar 

 organ termed the " spinneret," which is placed at the extremity 

 of tiie body. In consequence of its position, the spider always 

 hangs with its head downwards while lowering itself by means 

 of its line. 



The spinnerets are externally like little rounded projections, 

 arranged in pairs, and four, six, or eight in number. They are 

 variable in shape, mostly being rounded, but sometimes being so 

 long that they have been mistaken for feelers. The spinnerets 

 are covered with a multitude of very minute hair-like appendages, 

 which are, in fact, the _ tubes through which the liquid secretion 

 is forced into the air. All the threads which proceed from these 

 tubes are joined into a single line ; and it will be at once seen 

 that very great strength is obtained by making the line com- 

 pound instead of single. 



The best known of these creatures is the common Gakden 

 Spidee (Epeira diadema), sometimes called the Geometric Spideit, 

 whose beautifully radiated net is so familiar that its general 

 shape requires no description. Suffice it to say, that the spider 

 exhibits wonderful skill in placing its web, making a framework 

 of very strong threads or ropes, and then spinning the net itself 

 between them. Very great elasticity is thus obtained, for the 

 threads are exceedingly elastic ; so that, although stretched 

 tolerably tightly, they will yield to pressure, and immediately 

 recover themselves. This property is very needful, in order to 



