242 EVENINGS AT THE MICROSCOPE 



iong threads of silk which they spread about in the places 

 where they prowl in quest of prey. The Lapitelce, spin 

 great webs of a close texture, like hammocks, and wait for 

 the insects that may be entangled therein. The Orbitelce 

 spread abroad webs of a regular and open texture, either 

 circular or spiral, and remain in the middle, or on one 

 side, in readiness to spring upon an entangled insect. The 

 Retitelce spin webs of an open mesh-work and of an irregu- 

 lar form, and remain in the middle or on one side, to seize 

 their prey. Lastly, the Aquitelce spread their silken fila- 

 ments under water, to entrap aquatic insects. 



"The silken secretion of Spiders is not applied only to 

 the formation of a warm and comfortable dwelling for them- 

 selves, or of a trap for their prey; it is often employed to 

 master the struggles of a resisting insect, which is bound 

 round by an extemporary filament, spun for the occasion, 

 as by a strong cord. It forms the aeronautic filament of 

 the young migratory brood. It serves to attach the moult- 

 ing Hydrachna to an aquatic plant by the anterior part of 

 the body, when it struggles to withdraw itself from its ex- 

 uvium. Lastly, a softer and more silken kind of web is 

 prepared for the purpose of receiving the eggs, and to 

 serve as a nest for the young." ' 



The silk with which these various fabrics are con- 

 structed is a thick, viscous, transparent liquid, much like 

 a solution of gum arabic, which hardens quickly on expos- 

 ure to the air, but can meanwhile be drawn out into thread. 

 So far, it agrees with the silk of the silkworm and other 

 caterpillars; but the apparatus by which it is secreted, and 

 that by which it is spun, are both far more complex and 



1 "Comp. Anat." (Ed. 2), p. 458. 



