270 ANIMAL INTELLIGENCE 



design is not to be mistaken ; but who can suspect the 

 builder to be also the architect ? At a given period of 

 its growth the motor nerves of this sluggish larva set 

 in action machinery specialised to work up material 

 which has been unconsciously stored. The action is 

 wholly independent of the creature's volition. It Tnust 

 spin, whether it would or no, and it can exercise no 

 discretion in the style or shape of its cocoon. 



In the case of spiders we have the action of an adult 

 creature instead of a larva ; yet the process seems to be 

 none the less independent of volition. The design is 

 so much more ambitious than the silkworm's, the 

 structure so much more beautiful and complex, and so 

 closely in accord with the principles of human 

 engineering, that one has more difficulty in dissociating 

 it from the independent ingenuity and conscious skill 

 of the worker. Yet the common garden spider {Epeira 

 diadema) probably acts unconsciously in setting about 

 to spin her web. She (for it is only the female that 

 spins) does not reflect before setting in motion the 

 mechanism which she has inherited from a remote 

 ancestry, though she must exercise some discretion, 

 involving a mental process, in the choice of a site for her 

 web. She does not gaze with hungry longing upon the 

 flies disporting themselves in the sunshine, speculating 

 how, being wingless, she can capture those toothsome 

 flying creatures. Indeed, probably she cannot see them, 

 for the visual powers of web-spinning spiders are 

 believed to be very feeble, being compensated for by an 

 extraordinary refinement of the sense of touch. She 

 simply sets to work to apply the specialised mechanism 



