NOVEMBBE 271 



and material with which she is endowed to the purpose 

 for which they are co-ordinate. Although cut off by 

 the period spent as an egg in a cocoon from a parental 

 instruction or example, she is at no ' loss for a plan. 

 Innate functional impulse, which is probably the right 

 definition of what we term ' instinct,' co-ordinate with 

 certain specialised organs, directs the creature to the 

 unconscious performance of certain definite acts without 

 previous practice or experience. First, the foundations 

 are laid, in the shape of lines enclosing the area to be 

 occupied by the web. From this circumference the 

 radii or stays are drawn to the centre, whence the 

 spider works outwards, stepping from stay to stay and 

 laying down a thread in a wide spiral to act as 

 scaffolding for the finished structure. Finally, having 

 arrived at the limits of the operative net, she retraces 

 her steps, working inwards in a much closer spiral, 

 laying the transverse threads at the proper distance, 

 and devouring, as she goes, the original scaffolding 

 threads which enabled her to perform the work. 



If it is difficult to dissociate such a consummate 

 piece of engineering from the operation of a keen 

 intellect, still more so is it to regard the infinitely 

 greater complexity of the snares produced by certain 

 other spiders as the mere product of functional 

 automatism. Nevertheless, that seems to be the true 

 explanation. If the spider's web were the outcome of 

 the creature's individual ingenuity and intelligence, 

 there certainly would be manifest some variation in 

 the design among millions of webs by different 

 individuals of the same species — some imperfection 



