360 ARACHNIDA ARANEAE chap. 



of the House-spider, taken internally, was considered a specific 

 for the ague, though its value as a styptic has been recognised 

 in quite recent times. It is, however, with other uses of Spider 

 silk that we are here concerned. 



Spider silk has been extensively used in the micrometer eye- 

 pieces of telescopes where very fine intersecting lines are required. 

 Yov this purpose the radial or scaffolding lines of the circular 

 snare were selected, the spiral being unsuited on account of its 

 row of viscid beads. Professor C. V. Boys has, however, dis- 

 covered in his quartz fibres a material better adapted for this 

 purpose. 



Several attempts have been made to weave the silk of Spiders 

 as a substitute for that of the silk-worm. Web silk is, of course, 

 far too fine to furnish a durable material, but the cocoons are 

 usually formed of coarser silk, and it is with them that the 

 experiment has been tried. About the beginning of the eighteenth 

 century certain stockings and mittens made of Spider silk from 

 the cocoons of Eijeira diademata, by M. Bon of Languedoc, 

 attracted so much attention that the Academy desired M. Eeaumur 

 to investigate the matter. His report was unfavourable to the 

 commercial utility of Spider silk. The cocoon threads, though 

 eighteen times stronger than those of the web, were but one-fifth 

 of the strength of those obtained from the silk-worm, and the 

 lustre was inferior. A still more fatal objection, however, was 

 founded upon the cannibalistic habits of the spider, and the 

 difficulty of furnishing it with acceptable food. 



M. Vinson has recorded that some of the spiders of Madagascar, 

 especially Epeira madagascarensis, are far better adapted than 

 any of our Engiisli species to a commercial use. They furnish 

 silk of a beautiful clear yellow colour ; they are accustomed 

 to live harmoniously together in families ; and the range of 

 climate in which they can thrive is very considerable. The 

 Creole ladies of tliis island, under the administration of General 

 Decaen, wove a magnificent pair of gloves from spider silk, with 

 their own hands, for presentation to the French Empress. 



Poison of Spiders. — All spiders possess poison -glands, 

 which have their openings on the fangs of the chelicerae. The 

 action of the chelicera in striking does not express the venom, 

 but the poison-bag itself is covered with a muscular coat by 

 which the contained fluid is expelled. It is highly probable, 



