248 EVENINGS AT THE MICROSCOPE. 



of moving as an Egyptian mummy. To allow the 

 Spider to perform sucli a feat as this, its thread must 

 evidently be instantaneously placed at its disposal, 

 which would have been impossible had it been a single 

 cord, but being subdivided into numerous filaments, so 

 attenuated as we have seen them to be, there is no time 

 lost in the drying ; from being fluid they are at once 

 converted into a solid rope, ready for immediate ser- 

 vice." * 



ISTo doubt you have often admired the exquisite re- 

 gularity of those Spiders' webs which are called geo- 

 metric ; that of our abundant Garden Spider, for in- 

 stance. You have observed the cables which stretch 

 from wall to wall, or from bush to bush, in various di- 

 rections, to form the scaff'olding, on which the net is 

 afterwards to be woven ; then you have marked the 

 straight lines, like the spokes of a wheel, that radiate 

 from the centre to various points of these outwork 

 cables, and finally the spiral thread that circles again 

 and again round the radii, till an exquisite net of many 

 meshes is formed. 



But possibly you are not aware that these lines are 

 formed of two quite distinct sorts of silk. It has been 

 shown that the cables and radii are perfectly unad- 

 hesive, while the concentric or spiral circles are extreme- 

 ly viscid. 'Now the microscope, or a powerful lens, 

 will reveal the cause of this difference ; the threads of 

 the cables and radii are perfectly simple, while the 

 spiral threads are closely studded with minute globules 

 of fluid, like drops of dew, which, from the elasticity 

 of the thread, are easily separated from each other. 

 These are globules of viscid gum, as is easily proved by 



* Nat. Hist, of Anim. ii. 339. 



