GEOMETRICAL SPIDERS 93 



wonderful by knowing something of the manner of 

 that work. The spider is not degraded because at the 

 centre it can measure equal angles, at the circum- 

 ference equal arcs. Would not man act similarly 

 under like conditions? Would it not be a simple 

 method of drawing equidistant radii from the centre of 

 a circle to take equidistant points upon the circum- 

 ference and then join them to the centre. ? Would 

 it not be a simple method to measure the angles at 

 the centre to see that no radius had been left out ? 

 The spider has adopted human methods ; it works 

 on geometrical lines. Its limbs are its dividers and 

 its measuring rule. By their aid the snare assumes 

 those accurate proportions that we never cease to 

 admire. Man can do but little better were he faced 

 with the construction of a similar snare. Each would 

 work on similar principles, the one knowingly, the 

 other instinctively. The spider, like man, is a 

 geometer. Assuredly by being so it is not degraded. 

 Rather must we not wonder at similar methods 

 existing in the highest and the humblest creatures 

 so far distant in the tree of life. 



Before leaving the radii I must mention a little 

 detail with regard to their structure, since it is a special 

 adjustment designed to give them additional strength. 

 Each radius is so constructed as to consist of a double 

 line. The method of duplication takes place in this 

 way. The spider during its examination at the hub 

 discovers an interval where no radius has yet been 

 laid down. It immediately hurries out along one of 

 the radii that bounds this interval and of course 

 pays out its filament of silk behind it. It reaches the 

 circumference, takes its four paces along the founda- 



